MEMS device and method for manufacturing MEMS device

Abstract

To provide a micro electro mechanical systems (MEMS) device which can suppress increase in electrostatic attraction and a driving voltage for inclining a movable part.SOLUTION: A micro electro mechanical systems (MEMS) device includes a movable part which is rotatable around a rotation shaft extending in a first direction, a first arm which crosses in the first direction and extends in a second direction away from the movable part from the movable part, and a second arm extending in a third direction opposite to the second direction from the movable part. At least a part of the movable part contains a first material. The first arm and the second arm contain a second material different from the first material.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a MEMS device having a rotatable movable part and a method for manufacturing the MEMS device.

Background Art

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

[0003] The MEMS device disclosed in Patent Document 1 includes a torsion spring extending along the X axis, a movable part having a mirror connected to the torsion spring, and a capacitance part. The capacitance part is composed of a first layer integrally formed with the movable part and a second layer separate from the first layer. The inclination of the movable part is realized by an electrostatic force generated by the engagement of a plurality of teeth provided in the first layer and a plurality of teeth provided in the second layer.

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, the movable part and the first layer of the capacitance part are integrated. Therefore, a large electrostatic attractive force and driving voltage are required to tilt the movable part, resulting in a large consumption current.

[0006] Accordingly, an object of the present disclosure is to solve the above problems and to provide a MEMS device capable of suppressing an increase in electrostatic attraction and driving voltage for tilting a movable part.

Means for Solving the Problems

[0007] A MEMS device according to an aspect of the present disclosure includes: a movable part rotatable about a rotation axis extending in a first direction; a first arm extending from the movable part in a second direction intersecting the first direction and away from the movable part; a second arm extending from the movable part in a third direction opposite to the second direction; at least a part of the movable part includes a first material; the first arm and the second arm include a second material different from the first material.

Advantages of the Invention

[0008] According to the present disclosure, it is possible to provide a MEMS device capable of suppressing an increase in electrostatic attraction and driving voltage for tilting a movable part.

Brief Description of the Drawings

[0009]

Figure 1

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Embodiments for Carrying Out the Invention

[0010] 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. The drawings are schematic, and the ratios of each dimension etc. do not necessarily match the actual ones. In the following description, terms indicating a specific direction or position (for example, terms including "up", "down", "right", "left", "front", "rear") may be used as necessary. 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 intersecting the thickness direction of the MEMS device (directions orthogonal in the following respective embodiments and drawings). The X direction and the Y direction intersect (orthogonal to each other in the following respective embodiments and drawings). The direction of the arrow in the X direction is an example of the second direction. The direction opposite to the arrow in the X direction is an example of the third direction. That is, the second direction and the third direction are opposite to each other. The Y direction is an example of the first direction. The Z direction is an example of the fourth 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.

[0011] <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 FIG. 2 and the left side views of FIGS. 3 to 16 described later, the illustration of what is behind the first arm 51 and the second arm 61 and what is in front of the first arm 51 and the second arm 61 is omitted. What is behind the first arm 51 and the second arm 61 is, for example, the first support portion 30 and the second support portion 40. What is in front of the first arm 51 and the second arm 61 is, for example, the torsion suspension structure 251.

[0012] The MEMS device 10 shown in FIGS. 1 and 2 may be provided with one or more layers stacked in the Z direction. Each of the one or more 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.

[0013] As shown in FIGS. 1 and 2, the MEMS device 10 includes a movable part 20, a first support part 30, a second support part 40, first arms 51 and 52, and second arms 61 and 62.

[0014] The movable part 20 is supported by the first support part 30 via the first arms 51 and 52, and is supported by the second support part 40 via the second arms 61 and 62.

[0015] Both sides of the movable part 20 in the Y direction are supported by a frame (not shown). In the first embodiment, the torsion suspension structures 251 and 252 of the movable part 20 are supported by the frame. Each of the torsion suspension structures 251 and 252 includes a torsion spring 25A. The torsion spring 25A extends along the Y direction and is twistable. The movable part 20 is rotatable about the torsion spring 25A when the torsion spring 25A is twisted. When viewed along the Y direction, the axis located at the center of the torsion spring 25A and extending along the Y direction is the rotation axis 101. That is, the movable part 20 is rotatable about the rotation axis 101. The torsion suspension structures 251 and 252 including the torsion spring 25A will be described later.

[0016] The movable part 20 includes a main body part 21, a reflector 22, connecting parts 231 and 232, a thin film part 241, and torsion suspension structures 251 and 252.

[0017] The main body part 21 includes a frame part 210 and joints 211 and 212.

[0018] The frame portion 210 has a frame shape. In the first embodiment, the frame portion 210 has an upper surface 201, a lower surface (not shown), side surfaces 203, 204, 205, and 206. The upper surface 201 and the lower surface are surfaces extending in the X direction and the Y direction. The side surfaces 203 and 204 are surfaces extending in the X direction and the Z direction. The side surfaces 205 and 206 are surfaces extending in the Y direction and the Z direction. The rotation axis 101 passes through the side surfaces 203 and 204. In this specification, the direction of the arrow in the Z direction is defined as "up", and the direction opposite to the arrow in the Z direction is defined as "down".

[0019] The joints 211 and 212 are provided at both ends of the main body portion 21 in the Y direction. The joint 211 is provided on the side surface 203 of the main body portion 21. The joint 212 is provided on the side surface 204 of the main body portion 21.

[0020] The reflector 22 is rotatably supported by the main body portion 21 about a rotation axis 102 extending along the X direction. In the first embodiment, the reflector 22 is a mirror. Note that the structure and operation of the reflector 22 are known. Therefore, further detailed description of the reflector 22 is omitted here.

[0021] The connection portions 231 and 232 are located on the surfaces of the joints 211 and 212. In the first embodiment, as shown in FIG. 2, the connection portion 231 is located on the side surface 211A of the joint 211. Further, the connection portion 231 is located on the bottom surface 211B of the joint 211 via the thin film portion 241. As shown in FIG. 1, the connection portion 232 provided on the surface of the joint 212 is also located on the side surface 212A of the joint 212 and is located on the bottom surface (not shown) of the joint 212 via the thin film portion 241, similar to the connection portion 231.

[0022] Note that the connection portions 231 and 232 may be located on surfaces of the joints 211 and 212 other than the side surface 211A and the bottom surface 211B. For example, the connection portion 231 may be located on the side surface 211C or the upper surface 211D of the joint 211 shown in FIG. 2.

[0023] As shown in FIG. 2, the thin film portion 241 is located between the bottom surface 211B of the joint 211 and the connection portion 231. Although not shown, the thin film portion 241 is also located between the bottom surface of the joint 212 and the connection portion 232.

[0024] As shown in FIG. 1, the torsion suspension structure 251 is fixed to the joint 211, and the torsion suspension structure 252 is fixed to the joint 212.

[0025] The torsion suspension structure 251 includes a torsion spring 25A and a fixing portion 25B. One end of the torsion spring 25A is fixed to the joint 211 and extends from the joint 211 along the rotation axis 101. The other end of the torsion spring 25A is fixed to the fixing portion 25B. When the MEMS device 10 is supported by an external housing (not shown), the fixing portion 25B is supported by the frame of the external housing. The torsion suspension structure 252 has the same configuration as the torsion suspension structure 251 and includes a torsion spring 25A and a fixing portion 25B. The torsion spring 25A fixed to the joint 212 extends from the joint 212 along the rotation axis 101.

[0026] One of the functions of the torsion suspension structures 251 and 252 is to support the main body portion 21 and reduce the movement of the movable portion 20 in the X direction or the Z direction. Further, the torsion suspension structures 251 and 252 can reduce the driving force required to rotate the movable portion 20.

[0027] In the movable portion 20, the main body portion 21, the reflector 22, the torsion suspension structures 251 and 252, the connection portions 231 and 232, and the thin film portion 241 are made of different materials from each other.

[0028] In the first embodiment, the main body 21, the reflector 22, and the torsion suspension structures 251 and 252 include silicon (Si), which is a single crystal material, as the main material. The connection parts 231 and 232 include polysilicon (Poly-Si), which is a polycrystalline material, as the main material. The coefficient of thermal expansion of polysilicon is substantially the same as that of silicon and is greater than the coefficient of thermal expansion of silicon. The main material of the main body 21, the reflector 22, and the torsion suspension structures 251 and 252 (silicon in the first embodiment) is an example of a first material. The main material of the connection parts 231 and 232 (polysilicon in the first embodiment) is an example of a second material.

[0029] In the first embodiment, the thin film part 241 includes silicon dioxide (SiO2) as the main material. The main material of the thin film part 241 (silicon dioxide in the first embodiment) is an example of a third material.

[0030] Note that the main body 21, the reflector 22, and the torsion suspension structures 251 and 252 may use a material other than silicon as the main material, or may use a material other than a single crystal material as the main material. The connection parts 231 and 232 may use a material other than polysilicon as the main material, or may use a material other than a polycrystalline material as the main material. The thin film part 241 may use a material other than silicon dioxide as the main material. The main body 21, the reflector 22, the torsion suspension structures 251 and 252, the connection parts 231 and 232, and the thin film part 241 may contain materials other than the main material, or may be composed of only the main material.

[0031] Note that it is desirable that the coefficient of thermal expansion of the first material included in the main body 21 and the torsion suspension structures 251 and 252 is substantially the same as the coefficient of thermal expansion of the second material included in the connection parts 231 and 232. However, the coefficient of thermal expansion of the first material and the coefficient of thermal expansion of the second material do not have to be substantially the same. Also, it is desirable that the coefficient of thermal expansion of the second material is equal to or greater than the coefficient of thermal expansion of the first material. However, the coefficient of thermal expansion of the second material may be less than the coefficient of thermal expansion of the first material.

[0032] As shown in FIG. 1, 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, in the X direction, the movable portion 20 is sandwiched between the first support portion 30 and the second support portion 40.

[0033] The first support portion 30 includes a support beam 31 and a transducer structure 32 (or a converter structure 32). The transducer structure 32 includes a stationary comb-shaped electrode 33 that does not move and a movable comb-shaped electrode 34 that can move. The first arms 51 and 52 are connected to the support beam 31. Thereby, the support beam 31 supports the movable portion 20 via the first arms 51 and 52. 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.

[0034] Each of the stationary comb-shaped electrode 33 and the movable comb-shaped electrode 34 includes one busbar electrode 35 and a plurality of finger electrodes 36 extending along the Y direction from the busbar electrode 35. In FIG. 1, the stationary comb-shaped electrode 33 includes four finger electrodes 36, and the movable comb-shaped electrode 34 includes five finger electrodes 36, but the number of finger electrodes 36 is not limited to the above number.

[0035] The busbar electrode 35 of the stationary comb-shaped electrode 33 and the busbar electrode 35 of the movable comb-shaped electrode 34 are arranged to face each other in the Y direction. The plurality of finger electrodes 36 included in the stationary comb-shaped electrode 33 and the plurality of finger electrodes 36 included in the movable comb-shaped electrode 34 are interposed with each other. The finger electrodes 36 of the stationary comb-shaped electrode 33 and the finger electrodes 36 of the movable comb-shaped electrode 34 adjacent to each other in the X direction constitute an electrode pair.

[0036] When a voltage is applied between the electrode pairs of the stationary comb-shaped electrode 33 and the movable comb-shaped electrode 34, the movable comb-shaped electrode 34 moves so that each electrode pair approaches or separates. That is, the movable comb-shaped electrode 34 moves so as to approach or separate from the stationary comb-shaped electrode 33 along the X direction. Thereby, the support beam 31 to which the movable comb-shaped electrode 34 is fixed also moves along the X direction.

[0037] In the above-described configuration, the first support portion 30 includes a support beam 31 and a transducer structure 32. The support beam 31 to which the first arms 51 and 52 are connected by voltage application moves along the X direction.

[0038] The second support portion 40 includes a support beam 41 and a transducer structure 42 (or a converter structure 42 in other words). The transducer structure 42 includes a stationary comb-shaped electrode 43 and a movable comb-shaped electrode 44. The second arms 61 and 62 are connected to the support beam 41. Thereby, the support beam 41 supports the movable portion 20 via the second arms 61 and 62. A 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.

[0039] The second support portion 40 has the same configuration as the first support portion 30. Therefore, further detailed description of the second support portion 40 is omitted. The support beam 41 and the transducer structure 42 respectively correspond to the support beam 31 and the transducer structure 32. Also, the stationary comb-shaped electrode 43, the movable comb-shaped electrode 44, the bus bar electrode 45, and the finger electrode 46 respectively correspond to the stationary comb-shaped electrode 33, the movable comb-shaped electrode 34, the bus bar electrode 35, and the finger electrode 36.

[0040] In addition, in the first embodiment and each of the embodiments described later, the configurations of the first support portion 30 and the second support portion 40 are not limited to the above-described configurations. The first support portion 30 and the second support portion 40 can be of any known configuration on the condition that the portions to which the first arms 51 and 52 and the second arms 61 and 62 are connected are movable along the X direction.

[0041] For example, in the configuration shown in FIG. 1, the stationary comb-shaped electrode 33 and the movable comb-shaped electrode 34 are provided between the support beam 31 and the movable portion 20, but the support beam 31 may be provided between the stationary comb-shaped electrode 33 and the movable comb-shaped electrode 34 and the movable portion 20.

[0042] As shown in FIGS. 1 and 2, the first arms 51 and 52 extend from the connection part 231 of the movable part 20 to the first support part 30. That is, the first arms 51 and 52 extend from the movable part 20 in the direction of the arrow in the X direction, which is the direction away from the movable part 20. One end parts of the first arms 51 and 52 are connected to the connection part 231. The other end parts of the first arms 51 and 52 are connected to the support beam 31 of the first support part 30.

[0043] The second arms 61 and 62 extend from the connection part 231 of the movable part 20 to the second support part 40. That is, the second arms 61 and 62 extend from the movable part 20 in the direction opposite to the arrow in the X direction. One end parts of the second arms 61 and 62 are connected to the connection part 231. The other end parts of the second arms 61 and 62 are connected to the support beam 41 of the second support part 40.

[0044] In the first embodiment, the thickness of the first arms 51 and 52 (in other words, the length of the first arms 51 and 52 in the Z direction) is 2 μm or more and 20 μm or less. Similarly, the thickness of the second arms 61 and 62 is also 2 μm or more and 20 μm or less. Preferably, the thickness of the first arms 51 and 52 and the second arms 61 and 62 is 2 μm or more and 10 μm or less. Note that the thickness of the first arms 51 and 52 and the second arms 61 and 62 is not limited to the above-described range.

[0045] In the first embodiment, the length of the first arms 51 and 52 and the second arms 61 and 62 in the X direction is 1200 μm. Note that the length of the first arms 51 and 52 and the second arms 61 and 62 in the X direction is not limited to 1200 μm.

[0046] Hereinafter, the connection between the first arms 51 and 61 and the connection part 231 will be described in detail. Note that the connection between the first arm 52 and the second arm 62 and the connection part 232 is the same as the connection between the first arms 51 and 61 and the connection part 231. Therefore, hereinafter, the description of the connection between the first arm 52 and the second arm 62 and the connection part 232 will be omitted.

[0047] As shown in FIG. 2, when viewed along the Y direction, the rotation axis 101 is located at the center of the portion composed of the joint 211 and the connection portion 231. The connection position 20A between the first arm 51 and the connection portion 231 of the movable portion 20 in the Z direction is located at the lower end of the movable portion 20 in the Z direction. The connection position 20B between the second arm 61 and the connection portion 231 of the movable portion 20 in the Z direction is located at the upper end of the movable portion 20 in the Z direction. That is, the rotation axis 101 is located between the connection position 20A and the connection position 20B.

[0048] Note that the position of the rotation axis 101 when viewed along the Y direction is not limited to the center of the portion composed of the joint 211 and the connection portion 231, and may be, for example, a position shifted either upward or downward with respect to the center portion. Further, the connection position 20A may be located other than the lower end of the movable portion 20, and the connection position 20B may be located other than the upper end of the movable portion 20.

[0049] <Operation of the MEMS device 10 according to the first embodiment> As described above, when a voltage is applied between each electrode pair of the stationary comb-shaped electrode 33 and the movable comb-shaped electrode 34, the movable comb-shaped electrode 34 moves so as to approach or separate from the stationary comb-shaped electrode 33 along the X direction. As a result, the support beam 31 to which the movable comb-shaped electrode 34 is fixed also moves along the X direction.

[0050] Similarly, when a voltage is applied between each electrode pair of the stationary comb-shaped electrode 43 and the movable comb-shaped electrode 44, the movable comb-shaped electrode 44 moves so as to approach or separate from the stationary comb-shaped electrode 43 along the X direction. As a result, the support beam 41 to which the movable comb-shaped electrode 44 is fixed also moves along the X direction.

[0051] As shown in FIG. 2, when the support beams 31 and 41 move away from the movable portion 20, a force 111 acts on the movable portion 20 via the first arms 51 and 52, and a force 112 acts on the movable portion 20 via the second arms 61 and 62. As a result, the movable portion 20 rotates in the direction indicated by the arrow 113 about the rotation axis 101.

[0052] Further, as the support beams 31 and 41 move closer to the movable part 20, a force 114 acts on the movable part 20 via the first arms 51 and 52, and a force 115 acts on the movable part 20 via the second arms 61 and 62. As a result, the movable part 20 rotates in the direction indicated by the arrow 116 about the rotation axis 101.

[0053] <Manufacturing method of MEMS device according to the first embodiment> Hereinafter, with reference to FIGS. 3 to 6, a manufacturing method of the MEMS device 10 according to the first embodiment will be described. In FIGS. 3 to 6, the manufacturing methods of the joint 211 of the movable part 20, the first arm 51, and the second arm 61 among the MEMS device 10 are described, and the manufacturing methods of the other parts of the MEMS device 10 are omitted. However, the other parts of the MEMS device 10 can also be manufactured by the same steps as the method described below. Note that, similarly, in the manufacturing methods of the MEMS devices according to the second and fourth embodiments described later, the manufacturing methods of the joint 211 of the movable part 20, the first arm 51, and the second arm 61 are described, and the manufacturing methods of the other parts are omitted. FIGS. 3 to 6 are left side views for explaining an example of the manufacturing method of the MEMS device according to the first embodiment of the present disclosure.

[0054] As shown in FIG. 3, a wafer 70 is manufactured. The wafer 70 has first member layers 711 and 712 and etching stop layers 721 and 722. These four layers are laminated in the order of the etching stop layer 721, the first member layer 711, the etching stop layer 722, and the first member layer 712 by known means. The etching stop layers 721 and 722 are examples of thin film portions.

[0055] At least a part of the wafer 70 contains a first material. In the first embodiment, at least a part of the first member layers 711 and 712 contains silicon, which is an example of the first material, and at least a part of the etching stop layers 721 and 722 contains silicon dioxide, which is an example of a third material.

[0056] Next, as shown in FIG. 4, a part of the first member layer 711 and a part of the etching stop layer 721 are removed by known means. For example, first, a part of the etching stop layer 721 is removed by wet etching, and then a part of the first member layer 711 is removed by dry etching. In this manufacturing method, at this time, the surface of the etching stop layer 721 other than the said part is covered with a photoresist (not shown). Thereby, among the first member layer 711 and the etching stop layer 721, while removing a desired part, the part other than the said desired part can be left.

[0057] By removing a part of the first member layer 711 and a part of the etching stop layer 721, the wafer 70 has a first plane 70A, a second plane 70B, and a step surface 70C. The first plane 70A is included in the etching stop layer 722. The second plane 70B is included in the etching stop layer 721 and is at a position different from the first plane 70A in the Z direction orthogonal to the first plane 70A. The step surface 70C is included in the first member layer 711 and is connected to the first plane 70A and the second plane 70B.

[0058] Next, as shown in FIG. 5, a second member layer 73 is laminated on the first plane 70A, the second plane 70B, and the step surface 70C. In the first embodiment, at least a part of the second member layer 73 includes polysilicon, which is an example of a second material. The second member layer 73 is an example of a member layer.

[0059] After laminating the second member layer 73, a part of the wafer 70 other than the part including a part of the second plane 70B and the step surface 70C is removed by known means. Here, the second plane 70B to be removed is continuous with the step surface 70C. For example, first, all of the first member layer 712 is removed by dry etching. Next, all of the etching stop layer 722 is removed by wet etching. Next, the part other than the said part of the first member layer 711 is removed by dry etching. Next, the part other than the said part of the etching stop layer 721 is removed by wet etching.

[0060] As a result, as shown in FIG. 6, the movable part 20, the first arm 51, and the second arm 61 are formed. In FIG. 6, the movable part 20 has the remaining wafer 70 (in other words, the first member layer 711 and the etching stop layer 721), and the portion in contact with the wafer 70 (in other words, the first member layer 711 and the etching stop layer 721) in the second member layer 73. The joint 211 of the movable part 20 has the remaining first member layer 711. The thin film part 241 of the movable part 20 has the remaining etching stop layer 721. The connection part 231 of the movable part 20 has the portion in contact with the wafer 70 in the second member layer 73.

[0061] In addition, the first arm 51 has the portion that was in contact with the first plane 70A of the removed wafer 70 in the second member layer 73. Further, the second arm 61 has the portion that was in contact with the second plane 70B of the removed wafer 70 in the second member layer 73.

[0062] The MEMS device 10 according to the first embodiment can exhibit the following effects. In addition, in MEMS devices other than the first embodiment described later, for configurations similar to those of the MEMS device 10, effects similar to those of the MEMS device 10 can be exhibited.

[0063] According to the first embodiment, the movable part 20 is supported by the first arms 51, 52 and the second arms 61, 62. The thinner the first arms 51, 52 and the second arms 61, 62 are, the more the movable part 20 can be rotated with a small electrostatic attraction force and driving voltage. Hereinafter, the first arms 51, 52 and the second arms 61, 62 are also referred to as arms.

[0064] It is desirable that the arms be maintained in a straight stretched state. However, when the thermal expansion coefficient of the movable part 20 and the thermal expansion coefficient of the arms are significantly different, the arms may bend due to the difference in the ratio of thermal expansion between the movable part 20 and the arms. According to the first embodiment, the thermal expansion coefficient of the movable part 20 and the thermal expansion coefficient of the arms are substantially the same. Therefore, the bending of the arms can be reduced.

[0065] When the coefficient of thermal expansion of the movable part 20 is larger than that of the arm, the arm may bend due to being pressed by the expanded movable part 20. According to the first embodiment, the coefficient of thermal expansion of the arm is equal to or greater than that of the movable part 20. Therefore, compared with the case where the coefficient of thermal expansion of the movable part 20 is larger than that of the arm, the bending of the arm can be reduced.

[0066] According to the first embodiment, the first material included in the movable part 20 is silicon, which is a single crystal material. Also, the second material included in the arm is polysilicon, which is a polycrystalline material. Thereby, the joining of the movable part 20 and the arm is easy. Also, the joining force between the movable part 20 and the arm can be strengthened.

[0067] According to the first embodiment, the movable part 20 can be rotated by making the force acting on the first arms 51 and 52 and the force acting on the second arms 61 and 62 be in opposite directions to each other.

[0068] According to the first embodiment, the first arms 51 and 52, the second arms 61 and 62, and the connecting parts 231 and 232 include the same material and are connected to each other. Therefore, in the manufacturing process of the MEMS device 10, the first arms 51 and 52, the second arms 61 and 62, and the connecting parts 231 and 232 can be formed in the same process. Thereby, the thickness variation between the first arms 51 and 52 and the second arms 61 and 62 can be reduced.

[0069] In the first embodiment, the thin film portion 241 is a residue of the etching stop layer 721 used when forming the movable portion 20 by etching in the manufacturing process of the MEMS device 10. In this case, in order to manufacture a MEMS device without the thin film portion 241, a process of removing the thin film portion 241 is separately required. However, in the MEMS device having the thin film portion 241 as in the first embodiment, the process of removing the thin film portion 241 in the manufacturing process is unnecessary. That is, according to the first embodiment, the manufacturing process of the MEMS device 10 can be reduced.

[0070] As described above, by forming the first arms 51 and 52 and the second arms 61 and 62 on the wafer 70 in addition, the thin first arms 51 and 52 and the second arms 61 and 62 of 2 μm to 10 μm or 2 μm to 20 μm can be formed as in the first embodiment.

[0071] The MEMS device 10 and its manufacturing method according to the first embodiment can exhibit the following effects. In MEMS devices other than the first embodiment described later, for configurations similar to those of the MEMS device 10, the same effects as those of the MEMS device 10 can be exhibited. Also, in the manufacturing methods of MEMS devices other than the first embodiment described later, for manufacturing methods similar to the manufacturing method of the MEMS device 10, the same effects as those of the manufacturing method of the MEMS device 10 can be exhibited.

[0072] In the MEMS device 10, the arms are usually formed by removing a part of the wafer 70 by etching. However, generally, the etching rate of etching has a variation of about plus or minus 10%.

[0073] For example, when etching a part of the wafer 70 having a thickness of 100 μm to form an arm having a thickness of 10 μm, the depth of etching is 90 μm. The above variation is plus or minus 9 μm, which is 10% of this 90 μm. Then, the thickness of the formed arm has a variation of 10 μm plus or minus 9 μm, that is, 1 μm to 19 μm.

[0074] Due to the above variations, the arms formed by etching may become too thin, and in some cases, at least a part of the arms may be missing. Further, if there are variations in the thickness of the arms formed by etching, there may be variations in the rotation angle of the mirror part and displacement of the position of the rotation axis of the mirror part.

[0075] According to the first embodiment and its manufacturing method, the arms contain a material different from that of the movable part 20. Therefore, the arms can be formed not by removing a part of the wafer 70 by etching, but by forming a film in addition to the wafer 70. Generally, the variation in film formation is about plus or minus 10%.

[0076] For example, when forming an arm having a thickness of 10 μm, the variation in film formation is plus or minus 1 μm, which is 10% of this 10 μm. Then, the thickness of the formed arm has a variation of 10 μm plus or minus 1 μm, that is, 9 μm to 11 μm. Thus, according to the first embodiment and the manufacturing method, the variation in the thickness of the arms can be made smaller than when formed by etching.

[0077] According to the manufacturing method of the first embodiment, the thin film part 241 can be utilized as the etching stop layers 721 and 722 used when forming the movable part 20 by etching.

[0078] <Second Embodiment> FIG. 7 is a left side view showing a MEMS device according to the second embodiment of the present disclosure. Hereinafter, the differences from the first embodiment will be described. In the second embodiment and each of the embodiments described later, regarding the common points with the MEMS device 10 according to the first embodiment, the same reference numerals are given, and the description thereof is omitted in principle and will be described as necessary.

[0079] As shown in FIG. 7, in the MEMS device 10A, the movable part 20 may not include the thin film part 241. In the MEMS device 10A, the connection part 231 is located on the bottom surface 211B of the joint 211 without passing through the thin film part 241.

[0080] <Manufacturing method of MEMS device according to the second embodiment> Hereinafter, with reference to FIGS. 8 to 11, a manufacturing method of the MEMS device 10A according to the fourth embodiment will be described. FIGS. 8 to 11 are left side views for explaining an example of the manufacturing method of the MEMS device according to the second embodiment of the present disclosure.

[0081] As shown in FIG. 8, a wafer 70 similar to that of the first embodiment is manufactured. However, in the wafer 70 shown in FIG. 8, the etching stop layer 721 is provided only in a part of the first member layer 711.

[0082] At least a part of the wafer 70 contains a first material. In the second embodiment, as in the first embodiment, at least a part of the first member layers 711 and 712 contains silicon, which is an example of the first material, and at least a part of the etching stop layers 721 and 722 contains silicon dioxide, which is an example of the third material.

[0083] Next, as shown in FIG. 9, a part of the first member layer 711 is removed by known means such as dry etching. In this manufacturing method, at this time, the surfaces of the etching stop layer 721 and the first member layer 711 other than the said part are covered with photoresist. Thereby, while removing a desired part of the first member layer 711, the parts other than the desired part can be left.

[0084] By removing a part of the first member layer 711, the wafer 70 has a first plane 70A, a second plane 70B, and a step surface 70C. The first plane 70A is included in the etching stop layer 722. The second plane 70B is included in the etching stop layer 721 and the first member layer 711, and is at a position different from the first plane 70A in the Z direction orthogonal to the first plane 70A. The step surface 70C is included in the first member layer 711 and is connected to the first plane 70A and the second plane 70B.

[0085] Next, as shown in FIG. 10, the second member layer 73 is laminated on the first plane 70A, the second plane 70B, and the step surface 70C. In the second embodiment, at least a part of the second member layer 73 includes polysilicon, which is an example of the second material, in the same manner as in the first embodiment.

[0086] After laminating the second member layer 73, portions of the wafer 70 other than the portion including the step surface 70C and a part of the second plane 70B continuous with the step surface 70C are removed by known means. Here, a part of the second plane 70B continuous with the step surface 70C is the portion of the second plane 70B included in the first member layer 711. That is, the portion of the wafer 70 including the step surface 70C and a part of the second plane 70B continuous with the step surface 70C is the portion of the first member layer 711 that contacts the second member layer 73 without passing through the etching stop layer 721. Therefore, portions of the wafer 70 other than this portion are removed by known means.

[0087] For example, first, all of the first member layer 712 is removed by dry etching. Next, all of the etching stop layer 722 is removed by wet etching. Next, portions of the first member layer 711 other than the portion that contacts the second member layer 73 without passing through the etching stop layer 721 are removed by dry etching. Next, all of the etching stop layer 721 is removed by wet etching.

[0088] As a result, as shown in FIG. 11, the movable part 20, the first arm 51, and the second arm 61 are formed. In FIG. 11, the movable part 20 has the remaining wafer 70 (in other words, the first member layer 711) and the portion in the second member layer 73 that is in contact with the wafer 70 (in other words, the first member layer 711). The joint 211 of the movable part 20 has the remaining first member layer 711 described above. The connection part 231 of the movable part 20 has the portion in the second member layer 73 that is in contact with the first member layer 711.

[0089] Further, the first arm 51 has the portion in the second member layer 73 that was in contact with the first plane 70A of the removed wafer 70. Further, the second arm 61 has the portion in the second member layer 73 that was in contact with the second plane 70B of the removed wafer 70.

[0090] <Third Embodiment> FIG. 12 is a left side view showing a MEMS device according to the third embodiment of the present disclosure. Hereinafter, differences from the first embodiment will be described.

[0091] As shown in FIG. 12, in the MEMS device 10B, the movable part 20 may not include the connection parts 231 and 232. In the MEMS device 10B, the first arms 51 and 52 are in contact with the side surface 211C of the movable part 20, and the second arms 61 and 62 are in contact with the side surface 211A of the movable part 20.

[0092] <Fourth Embodiment> FIG. 13 is a left side view showing a MEMS device according to the fourth embodiment of the present disclosure. Hereinafter, differences from the first embodiment will be described.

[0093] As shown in FIG. 13, in the MEMS device 10C, when viewed along the Y direction, the rotation axis 101 is located at the center of the portion composed of the joint 211 and the connection portion 231. The connection position 20A between the first arm 51 in the Z direction and the connection portion 231 of the movable portion 20 is located at the lower end of the movable portion 20 in the Z direction. The connection position 20B between the second arm 61 in the Z direction and the connection portion 231 of the movable portion 20 is also located at the lower end of the movable portion 20 in the Z direction. That is, in the Z direction, the connection position 20A and the connection position 20B are at positions different from the rotation axis 101 and are located on the same side with respect to the rotation axis 101 (the lower side with respect to the rotation axis 101 in FIG. 13).

[0094] Note that the position of the rotation axis 101 when viewed along the Y direction is not limited to the center of the portion composed of the joint 211 and the connection portion 231, and may be, for example, the upper end or the lower end of the portion. Also, the connection positions 20A and 20B may be located other than the lower end of the movable portion 20. In the configuration shown in FIG. 13, the connection position 20A and the connection position 20B are at the same position in the Z direction, but the positions of the connection position 20A and the connection position 20B in the Z direction may be different. For example, the connection position 20A in the Z direction may be the lower end of the movable portion 20, and the connection position 20B in the Z direction may be between the rotation axis 101 and the connection position 20A.

[0095] Note that also in the MEMS device 10C according to the fourth embodiment, similar to the MEMS device 10A according to the second embodiment, the movable portion 20 may not include the thin film portion 241.

[0096] <Operation of the MEMS Device 10 According to the Fourth Embodiment> As described above, when a voltage is applied between each pair of electrodes of the stationary comb-shaped electrode 33 and the movable comb-shaped electrode 34, the movable comb-shaped electrode 34 moves so as to approach or move away from the stationary comb-shaped electrode 33 along the X direction. As a result, the support beam 31 to which the movable comb-shaped electrode 34 is fixed also moves along the X direction.

[0097] Similarly, when a voltage is applied between each pair of electrodes of the stationary comb-shaped electrode 43 and the movable comb-shaped electrode 44, the movable comb-shaped electrode 44 moves so as to approach or move away from the stationary comb-shaped electrode 43 along the X direction. As a result, the support beam 41 to which the movable comb-shaped electrode 44 is fixed also moves along the X direction.

[0098] As shown in FIG. 13, when the support beam 31 moves so as to approach the movable part 20, a force 117 acts on the movable part 20 via the first arms 51 and 52. Further, when the support beam 41 moves so as to move away from the movable part 20, a force 118 acts on the movable part 20 via the second arms 61 and 62. As a result, the movable part 20 rotates in the direction indicated by the arrow 119 about the rotation axis 101.

[0099] Further, when the support beam 31 moves so as to move away from the movable part 20, a force 120 acts on the movable part 20 via the first arms 51 and 52. Further, when the support beam 41 moves so as to approach the movable part 20, a force 121 acts on the movable part 20 via the second arms 61 and 62. As a result, the movable part 20 rotates in the direction indicated by the arrow 122 about the rotation axis 101.

[0100] <Manufacturing method of MEMS device according to the fourth embodiment> Hereinafter, a method for manufacturing the MEMS device 10C according to the fourth embodiment will be described with reference to FIGS. 14 to 16. FIGS. 14 to 16 are left side views for explaining an example of a method for manufacturing an MEMS device according to the fourth embodiment of the present disclosure.

[0101] As shown in FIG. 14, a wafer 70 is manufactured. The wafer 70 has a first member layer 711 and an etching stop layer 721. These two layers are laminated by known means.

[0102] At least a part of the wafer 70 contains a first material. In the fourth embodiment, at least a part of the first member layer 711 contains silicon, which is an example of the first material, and at least a part of the etching stop layer 721 contains silicon dioxide, which is an example of the third material.

[0103] Next, as shown in FIG. 15, a second member layer 73 is laminated on the surface of the etching stop layer 721, that is, on the main surface 70D of the wafer 70. In the fourth embodiment, as in the first embodiment, at least a part of the second member layer 73 contains polysilicon which is an example of the second material.

[0104] After the second member layer 73 is laminated, portions other than the central portion 74 of the wafer 70 are removed by known means. The central portion 74 is the central part of the wafer 70 when viewing the wafer 70 along the Z direction, and is the portion sandwiched by the broken lines in FIG. 15.

[0105] For example, first, a portion of the first member layer 711 excluding the central portion 74 is removed by dry etching. Next, a portion of the etching stop layer 721 excluding the central portion 74 is removed by wet etching.

[0106] Thereby, as shown in FIG. 16, the movable portion 20, the first arm 51, and the second arm 61 are formed. In FIG. 16, the movable portion 20 has the remaining wafer 70 (in other words, the first member layer 711 and the etching stop layer 721), and a portion in contact with the wafer 70 (in other words, the first member layer 711 and the etching stop layer 721) in the second member layer 73. The joint 211 of the movable portion 20 has the remaining first member layer 711. The thin film portion 241 of the movable portion 20 has the remaining etching stop layer 721. The connection portion 231 of the movable portion 20 has a portion in contact with the etching stop layer 721 in the second member layer 73.

[0107] Further, the first arm 51 and the second arm 61 have a portion in contact with the main surface 70D of the removed wafer 70 in the second member layer 73. The first arm 51 has a portion extending from the movable portion 20 in the second direction (in other words, the direction of the arrow in the X direction). The second arm 61 has a portion extending from the movable portion 20 in the third direction (in other words, the direction opposite to the arrow in the X direction).

[0108] In the case where the movable part 20 in the MEMS device 10C does not include the thin film part 241, the wafer 70 has the first member layer 711 but does not have the etching stop layer 721. Also, the main surface 70D of the wafer 70 is the surface of the first member layer 711, and the second member layer 73 is laminated on the surface.

[0109] The MEMS device 10C according to the fourth embodiment can exhibit the following effects.

[0110] According to the fourth embodiment, by making the force acting on the first arms 51 and 52 and the force acting on the second arms 61 and 62 have the same direction as each other, the movable part 20 can be rotated.

[0111] The MEMS device described above can also be expressed as follows.

[0112] (1) The MEMS device of the present disclosure is a movable part rotatable about a rotation axis extending in a first direction, a first arm extending from the movable part in a second direction intersecting the first direction and away from the movable part, a second arm extending from the movable part in a third direction opposite to the second direction, and includes at least a part of the movable part includes a first material, the first arm and the second arm include a second material different from the first material.

[0113] (2) In the MEMS device of (1), the coefficient of thermal expansion of the first material and the coefficient of thermal expansion of the second material may be substantially the same.

[0114] (3) In the MEMS device of (1) or (2), the coefficient of thermal expansion of the second material may be equal to or greater than the coefficient of thermal expansion of the first material.

[0115] (4) In any one of the MEMS devices according to (1) to (3), the first material may be a single crystal material, and the second material may be a polycrystalline material.

[0116] (5) In the MEMS device according to (4), the first material may be silicon, and the second material may be polysilicon.

[0117] (6) In any one of the MEMS devices according to (1) to (5), in a fourth direction intersecting the first direction and the second direction, the rotation axis may be located between the connection position of the movable part and the first arm and the connection position of the movable part and the second arm.

[0118] (7) In any one of the MEMS devices according to (1) to (5), in a fourth direction intersecting the first direction and the second direction, the connection position of the movable part and the first arm and the connection position of the movable part and the second arm may be at positions different from the rotation axis and on the same side with respect to the rotation axis.

[0119] (8) In any one of the MEMS devices according to (1) to (7), the movable part may include a main body part containing the first material, and a connection part containing the second material and connected to the first arm and the second arm.

[0120] (9) In the MEMS device according to (8), the movable part may include a thin film part containing a third material different from the first material and the second material, and the thin film part may be located between the main body part and the connection part.

[0121] (10) In any one of the MEMS devices (1) to (9), The lengths of the first arm and the second arm in a fourth direction intersecting the first direction and the second direction may be 2 μm or more and 20 μm or less.

[0122] (11) In the MEMS device of (10), The lengths of the first arm and the second arm in the fourth direction may be 2 μm or more and 10 μm or less.

[0123] (12) The manufacturing method of the MEMS device of the present disclosure is A movable part rotatable about a rotation axis extending in a first direction, a first arm extending from the movable part in a second direction intersecting the first direction and away from the movable part, and a second arm extending from the movable part in a third direction opposite to the second direction, at least a part of the movable part includes a first material, and the first arm and the second arm include a second material different from the first material, which is a manufacturing method of a MEMS device, In a wafer having a first plane, a second plane located at a position different from the first plane in a direction orthogonal to the first plane, and a stepped surface connected to the first plane and the second plane, a member layer containing the second material is laminated on the first plane, the second plane, and the stepped surface, After the lamination of the member layer, a part of the wafer other than the part including the stepped surface and a part of the second plane continuous with the stepped surface is removed to form the movable part having the wafer and the part of the member layer in contact with the wafer, and the first arm having the part of the member layer in contact with the first plane of the removed wafer is formed, and the second arm having the part of the member layer in contact with the second plane of the removed wafer is formed.

[0124] (13) In the manufacturing method of the MEMS device of (12), The wafer may include a thin film portion containing a third material different from the first material and the second material. The thin film portion may include the second plane.

[0125] (14) A method for manufacturing a MEMS device according to the present disclosure is a method for manufacturing a MEMS device, comprising: a movable part rotatable about a rotation axis extending in a first direction; a first arm extending from the movable part in a second direction intersecting the first direction and away from the movable part; and a second arm extending from the movable part in a third direction opposite to the second direction, at least a part of the movable part containing a first material, and the first arm and the second arm containing a second material different from the first material. A member layer containing the second material is laminated on a main surface of a wafer at least a part of which contains the first material. After the lamination of the member layer, portions other than the central portion of the wafer are removed to form the movable part having the wafer and the portion of the member layer in contact with the wafer, a first arm having a portion extending from the movable part in the second direction is formed in the member layer, and a second arm having a portion extending from the movable part in the third direction is formed in the member layer.

[0126] (15) In the method for manufacturing a MEMS device according to (14), the wafer may include a thin film portion containing a third material different from the first material and the second material. The thin film portion may include the main surface.

[0127] Note that by appropriately combining any of the various embodiments, the respective effects can be achieved.

[0128] The present invention is fully described in connection with preferred embodiments with reference to the drawings as appropriate, but various modifications and alterations will be apparent to those skilled in the art. Such modifications and alterations are to be understood as being included therein as long as they do not depart from the scope of the present invention as defined by the appended claims.

Explanation of Reference Numerals

[0129] 10 MEMS device 20 Movable part 20A Connection position 20B Connection position 21 Main body part 231 Connection part 232 Connection part 241 Thin film part 51 First arm 52 First arm 61 Second arm 62 Second arm 70 Wafer 70A First plane 70B Second plane 70C Step surface 70D Main surface 711 First member layer 712 First member layer 73 Second member layer (member layer) 74 Central part 101 Rotation axis

Claims

1. A movable part that is rotatable about a rotation axis extending in a first direction; a first arm extending from the movable portion in a second direction intersecting the first direction and away from the movable portion; a second arm extending from the movable portion in a third direction opposite to the second direction, At least a portion of the movable portion includes a first material; The first arm and the second arm comprise a second material different from the first material.

2. The MEMS device of claim 1 , wherein the first material and the second material have substantially the same coefficient of thermal expansion.

3. The MEMS device according to claim 1 or 2, wherein the second material has a coefficient of thermal expansion equal to or greater than the coefficient of thermal expansion of the first material.

4. the first material is a single crystal material; The MEMS device of claim 1 , wherein the second material is a polycrystalline material.

5. the first material is silicon; The MEMS device of claim 4 , wherein the second material is polysilicon.

6. 6. The MEMS device according to claim 1, wherein in a fourth direction intersecting the first direction and the second direction, the rotation axis is located between a connection position of the movable part and the first arm and a connection position of the movable part and the second arm.

7. 6. The MEMS device according to claim 1, wherein in a fourth direction intersecting the first direction and the second direction, a connection position of the movable part and the first arm and a connection position of the movable part and the second arm are located at a different position from the rotation axis and on the same side of the rotation axis.

8. The movable part is a body portion including the first material; The MEMS device of claim 1 , further comprising: a connection portion including the second material and connected to the first arm and the second arm.

9. the movable portion includes a thin film portion including a third material different from the first material and the second material, The MEMS device according to claim 8 , wherein the thin film portion is located between the main body portion and the connection portion.

10. The MEMS device according to claim 1 , wherein a length of the first arm and the second arm in a fourth direction intersecting the first direction and the second direction is not less than 2 μm and not more than 20 μm.

11. The MEMS device of claim 10 , wherein a length of the first arm and the second arm in the fourth direction is not less than 2 μm and not more than 10 μm.

12. 1. A method for manufacturing a MEMS device comprising: a movable part rotatable about a rotation axis extending in a first direction; a first arm extending from the movable part in a second direction intersecting the first direction and moving away from the movable part; and a second arm extending from the movable part in a third direction opposite to the second direction, wherein at least a portion of the movable part includes a first material, and the first arm and the second arm include a second material different from the first material, In a wafer at least a portion of which contains the first material, the wafer has a first plane, a second plane located at a position different from the first plane in a direction perpendicular to the first plane, and a step surface connected to the first plane and the second plane, a member layer containing the second material is laminated on the first plane, the second plane, and the step surface; a first arm having a portion of the component layer that was in contact with the first plane of the wafer that has been removed, and a second arm having a portion of the component layer that was in contact with the second plane of the wafer that has been removed, the first arm being formed having a portion of the component layer that was in contact with the second plane of the wafer that has been removed, after the component layers are stacked.

13. the wafer includes a thin film portion including a third material different from the first material and the second material; The method for manufacturing a MEMS device according to claim 12 , wherein the thin film portion includes the second plane.

14. 1. A method for manufacturing a MEMS device comprising: a movable part rotatable about a rotation axis extending in a first direction; a first arm extending from the movable part in a second direction intersecting the first direction and moving away from the movable part; and a second arm extending from the movable part in a third direction opposite to the second direction, wherein at least a portion of the movable part includes a first material, and the first arm and the second arm include a second material different from the first material, A member layer including the second material is laminated on a main surface of a wafer at least a portion of which includes the first material; a first arm formed in the component layer having a portion extending from the movable part in the second direction from the movable part; and a second arm formed in the component layer having a portion extending from the movable part in the third direction from the movable part.

15. the wafer includes a thin film portion including a third material different from the first material and the second material; The method for manufacturing a MEMS device according to claim 14 , wherein the thin film portion includes the main surface.

Images