MEMS device and method for manufacturing same

Abstract

A MEMS device (1) comprises a first device substrate (10) composed of single-crystal silicon, and a second device substrate (20) composed of single-crystal silicon, the MEMS device detecting the capacitance formed by the first device substrate (10), wherein: the first device substrate (10) has a bonding portion (14) that is directly bonded to the second device substrate (20), a movable portion (12) that is configured to be capable of moving away from the second device substrate (20), and a connection portion (13) that connects the bonding portion (14) and the movable portion (12); and the connection portion (13) is provided with a trench structure in which the distance (H2) between the connection portion (13) and the second device substrate (20) is greater than the distance (H1) between the movable portion (12) and the second device substrate (20).

Description

MEMS device and manufacturing method thereof

[0001] The present invention relates to a MEMS device and a method for manufacturing the same.

[0002] Micro Electro Mechanical Systems (MEMS) devices manufactured using MEMS technology are becoming widespread. MEMS devices are used, for example, in inertial sensors that detect acceleration and angular velocity based on changes in electrostatic capacitance. To improve the performance of MEMS devices, multi-layered MEMS structures have been proposed.

[0003] For example, Patent Document 1 discloses a micromechanical sensor in which a plurality of polycrystalline silicon layers are stacked.

[0004] U.S. Pat. No. 10,294,095

[0005] However, in the micromechanical sensor described in Patent Document 1, the stress of the polycrystalline silicon layer tends to cause warping of the micromechanical sensor, which may hinder high performance. Furthermore, to form a gap between the polycrystalline silicon layers, for example, a sacrificial layer such as a silicon oxide film is formed between the polycrystalline silicon layers, and multiple through-holes are provided in the polycrystalline silicon layer for removing the sacrificial layer by steam etching. Furthermore, space is required to provide such multiple through-holes, which reduces the space available for functioning as a sensor, which may hinder high performance.

[0006] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a MEMS device that can achieve high performance, and a method for manufacturing the same.

[0007] A MEMS device according to one aspect of the present invention comprises a first device substrate made of single crystal silicon and a second device substrate made of single crystal silicon, and is a MEMS device that detects the capacitance formed by the first device substrate, wherein the first device substrate has a bonding portion directly bonded to the second device substrate, a movable portion configured to be movable at a distance from the second device substrate, and a connecting portion that connects the bonding portion and the movable portion, and the connecting portion has a trench structure whose distance to the second device substrate is greater than the distance between the movable portion and the second device substrate.

[0008] Another aspect of the present invention relates to a method for manufacturing a MEMS device that detects capacitance formed by a first device substrate, the method including preparing a first device substrate made of single crystal silicon, preparing a second device substrate made of single crystal silicon, and directly bonding the first device substrate and the second device substrate, wherein preparing the first device substrate includes preparing a single crystal silicon substrate, forming a recessed structure in which the portion that will become the movable part is recessed relative to the portion that will become the joint, and forming a trench structure that is deeper than the recessed structure in the portion that will become the connecting part that connects the joint and the movable part.

[0009] According to the present invention, it is possible to provide a MEMS device that can achieve high performance and a method for manufacturing the same.

[0010] 3 is a cross-sectional view of a MEMS device according to a first embodiment. FIG. 4 is an enlarged plan view of the inside of the MEMS device according to the first embodiment. FIG. 5 is an enlarged cross-sectional view of the MEMS device taken along line III-III in FIG. 2. FIG. 6 is an enlarged cross-sectional view of the MEMS device taken along line IV-IV in FIG. 2. FIG. 6 is a cross-sectional view of a wiring portion. FIG. 7 is a cross-sectional view of a wiring portion in a modified example. FIG. 7 is a flowchart showing a method for manufacturing the MEMS device according to the first embodiment. FIG. 8 is a cross-sectional view showing the manufacturing process of the MEMS device. FIG. 9 is a cross-sectional view showing the manufacturing process of the MEMS device. FIG. 10 is a cross-sectional view showing the manufacturing process of the MEMS device. FIG. 11 is a cross-sectional view showing a modified example of the manufacturing process of the MEMS device. FIG. 12 is an enlarged cross-sectional view of a MEMS device according to a second embodiment. FIG. 13 is a cross-sectional view showing the manufacturing process of the MEMS device. FIG. 14 is a cross-sectional view showing the manufacturing process of the MEMS device.

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The drawings of the present embodiment are merely examples, and the dimensions and shapes of each part are schematic, so the technical scope of the present invention should not be interpreted as being limited to the embodiment.

[0012] First Embodiment First, the configuration of a MEMS device 1 according to a first embodiment of the present invention will be described with reference to Fig. 1. Fig. 1 is a cross-sectional view of the MEMS device according to the first embodiment.

[0013] Each component of the MEMS device 1 will be described below. For the sake of clarity and understanding of the positional relationships between the various components, each drawing may be accompanied by a Cartesian coordinate system consisting of an X-axis, a Y-axis, and a Z-axis. The directions parallel to the X-axis, the Y-axis, and the Z-axis are referred to as the X-axis, the Y-axis, and the Z-axis, respectively. The plane defined by the X-axis and the Y-axis is referred to as the XY plane. For the sake of convenience, the positive Z-axis direction (the direction of the arrow) will be referred to as the top or upper side, and the negative Z-axis direction (the direction opposite to the arrow) will be referred to as the bottom or lower side. However, the orientation of the MEMS device 1 is not limited to this.

[0014] The MEMS device 1 is a device manufactured using MEMS technology. The MEMS device 1 includes a first device substrate 10, a second device substrate 20, a first lid substrate 40, and a second lid substrate 30. The MEMS device 1 is a capacitance-type sensor that detects inertial forces (e.g., acceleration and angular velocity) and pressure in the X-axis, Y-axis, and Z-axis directions by detecting the capacitance formed by the first device substrate 10. The first lid substrate 40, the first device substrate 10, the second device substrate 20, and the second lid substrate 30 are stacked in this order in the Z-axis direction. The first lid substrate 40 is anodically bonded to the first device substrate 10, the first device substrate 10 is directly bonded to the second device substrate 20, and the second device substrate 20 is directly bonded to the second lid substrate 30. The first lid substrate 40 and the second lid substrate 30 form a package structure that defines a movable space within which the first device substrate 10 and the second device substrate 20 can move.

[0015] The first device substrate 10 is provided by a silicon substrate F10. The silicon substrate F10 is formed of single crystal silicon. The silicon substrate F10 is formed of, for example, a p-type silicon (Si) semiconductor. The silicon substrate F10 may contain boron (B) or the like as a p-type dopant. The resistance value of the silicon (Si) used in the silicon substrate F10 is, for example, about 10 mΩ·cm.

[0016] As shown in FIG. 1 , the first device substrate 10 includes movable portions 12A and 12B, connecting portions 13A and 13B, bonding portions 14A and 14B, conductive portions 17A and 17B, a support portion 18, and a peripheral portion 19. The movable portions 12A and 12B, connecting portions 13A and 13B, bonding portions 14A and 14B, conductive portions 17A and 17B, support portion 18, and peripheral portion 19 are formed by patterning a silicon substrate F10 through a removal process. The removal process is performed by dry etching, known as deep reactive ion etching (DRIE), for example. The removal process may also be performed by other techniques, such as wet etching and laser etching. The movable portions 12A and 12B are collectively referred to as the movable portion 12, the connecting portions 13A and 13B are collectively referred to as the connecting portion 13, and the joining portions 14A and 14B are collectively referred to as the joining portion 14.

[0017] Movable spaces 11A are provided between the first lid substrate 40 and the movable portions 12A and 12B, between the first lid substrate 40 and the connecting portions 13A and 13B, and between the first lid substrate 40 and the bonding portions 14A and 14B. Movable spaces 11B are provided between the second device substrate 20 and the movable portions 12A and 12B, and between the second device substrate 20 and the connecting portions 13A and 13B. In other words, the movable portions 12A and 12B are separated from both the first lid substrate 40 and the second device substrate 20. Furthermore, the movable portion 12A is separated from the rest of the first device substrate 10, except for the connecting portion 13A, by a slit penetrating the silicon substrate F10 in the Z-axis direction. The movable portion 12B is separated from the rest of the first device substrate 10, except for the connecting portion 13B, by a slit penetrating the silicon substrate F10 in the Z-axis direction. As a result, the movable portions 12A and 12B are configured to be movable.

[0018] The movable portion 12A serves as an electrode and weight for detecting inertial forces and pressures in the Z-axis direction. The movable portion 12A forms a capacitance with the first lid substrate 40, and also forms a capacitance with the second device substrate 20. When the MEMS device 1 is subjected to an inertial force or pressure in the Z-axis direction, the movable portion 12A is displaced in the Z-axis direction, and the gap between the movable spaces 11A and 11B in the Z-axis direction changes. Based on the change in the gap between the movable spaces 11A and 11B, the capacitance formed between the movable portion 12A and the first lid substrate 40 and the capacitance formed between the movable portion 12A and the second device substrate 20 change. By detecting these changes in both capacitances, the inertial force in the Z-axis direction applied to the MEMS device 1 can be detected.

[0019] The movable portion 12B serves as an electrode and weight for detecting inertial force and pressure in the X-axis direction. Multiple movable portions 12B are arranged at intervals in the X-axis direction, and electrostatic capacitance is formed between the movable portions 12B. When the MEMS device 1 is subjected to inertial force and pressure in the X-axis direction, the movable portions 12B are displaced in the X-axis direction. At this time, the ease of displacement of adjacent movable portions 12B differs, and therefore the distance between adjacent movable portions 12B changes. Based on this change in distance, the electrostatic capacitance formed by the movable portions 12B changes. By detecting this change in electrostatic capacitance, the inertial force and pressure in the X-axis direction applied to the MEMS device 1 can be detected.

[0020] Although not shown in the figure, the MEMS device 1 includes a plurality of movable parts spaced apart in the Y-axis direction. The inertial force or pressure in the Y-axis direction applied to the MEMS device 1 is detected by a change in the capacitance formed between the movable parts arranged in the Y-axis direction.

[0021] The connecting portion 13A connects the movable portion 12A and the joint portion 14A. The connecting portion 13B connects the movable portion 12B and the joint portion 14B. In the example shown in Fig. 1 , the connecting portion 13A is provided between the movable portion 12A and the joint portion 14A in the X-axis direction, and the connecting portion 13B is provided between the movable portion 12B and the joint portion 14B in the Y-axis direction.

[0022] The bonding portions 14A and 14B are bonded to the second device substrate 20 and fixed to the second device substrate 20. The bonding portion 14A is bonded to a bonding portion 24A of the second device substrate 20, which will be described later, and the bonding portion 14B is bonded to a bonding portion 24B of the second device substrate 20, which will be described later. The bonding between the bonding portion 14A and the bonding portion 24A and the bonding between the bonding portion 14B and the bonding portion 24B are direct bonding between single crystal silicon.

[0023] The movable portion 12A, the connecting portion 13A, and the bonding portion 14A are separated from other portions of the first device substrate 10 (such as the movable portion 12B, the connecting portion 13B, the bonding portion 14B, the conductive portions 17A and 18B, the support portion 18, and the peripheral portion 19) by slits that penetrate the silicon substrate F10 in the Z-axis direction. The movable portion 12B, the connecting portion 13B, and the bonding portion 14B are separated from other portions of the first device substrate 10 (such as the movable portion 12A, the connecting portion 13A, the bonding portion 14A, the conductive portions 17A and 18B, the support portion 18, and the peripheral portion 19) by slits that penetrate the silicon substrate F10 in the Z-axis direction.

[0024] Conductive portions 17A and 17B electrically connect the first lid substrate 40 and the first device substrate 10, and electrically connect the first lid substrate 40 and the second device substrate 20. Conductive portion 17A is bonded to an electrode provided on the first device substrate 10 side of the first lid substrate 40, and is bonded to a conductive portion 27A of the second device substrate 20, which will be described later. Conductive portion 17B is bonded to an electrode provided on the first device substrate 10 side of the first lid substrate 40, and is bonded to a conductive portion 27B of the second device substrate 20, which will be described later. The bond between conductive portion 17A and conductive portion 27A, and the bond between conductive portion 17B and conductive portion 27B are direct bonds between single crystal silicon. For example, conductive portion 17A electrically connects movable portion 12A to an external terminal provided on the side of first lid substrate 40 opposite to first device substrate 10, and conductive portion 17B electrically connects movable portion 12B to an external terminal provided on the side of first lid substrate 40 opposite to first device substrate 10. Conductive portion 17A is separated from other portions of first device substrate 10 (such as movable portions 12A and 12B, connecting portions 13A and 13B, bonding portions 14A and 14B, conductive portion 17B, support portion 18, and peripheral portion 19) by a slit penetrating silicon substrate F10 in the Z-axis direction. The conductive portion 17B is separated from other parts of the first device substrate 10 (such as the movable portions 12A, 12B, the connecting portions 13A, 13B, the bonding portions 14A, 14B, the conductive portion 17A, the support portion 18 and the peripheral portion 19) by a slit that penetrates the silicon substrate F10 in the Z-axis direction.

[0025] The support portion 18 supports the movable portions 12A and 12B, the connecting portions 13A and 13B, the bonding portions 14A and 14B, and the conductive portions 17A and 17B of the first device substrate 10. The support portion 18 also functions as a conductive portion that electrically connects the first lid substrate 40 and the first device substrate 10 and electrically connects the first lid substrate 40 and the second device substrate 20. The support portion 18 is bonded to an electrode provided on the first device substrate 10 side of the first lid substrate 40 and is bonded to a support portion 28 of the second device substrate 20, which will be described later. The bond between the support portion 18 and the support portion 28 is a direct bond between single-crystal silicon. The support portion 18 connects the first device substrate 10 to the first lid substrate 40 and connects the first device substrate 10 to the second lid substrate 30 via the second device substrate 20. The support portion 18 is separated from other parts of the first device substrate 10 (such as the movable portions 12A, 12B, the connecting portions 13A, 13B, the bonding portions 14A, 14B, the conductive portions 17A, 17B, and the peripheral portion 19) by a slit that penetrates the silicon substrate F10 in the Z-axis direction.

[0026] The peripheral portion 19 is provided in a frame shape along the outer edge of the first device substrate 10. When viewed in a plan view in the Z-axis direction (hereinafter simply referred to as "plan view"), the peripheral portion 19 surrounds the movable portions 12A, 12B, the connecting portions 13A, 13B, the bonding portions 14A, 14B, the conductive portions 17A, 17B, and the support portion 18. The peripheral portion 19 is bonded to an insulating portion of the first lid substrate 40 and to a peripheral portion 29 of the second device substrate 20 (described later). The bonding between the peripheral portion 19 and the first lid substrate 40 is, for example, anodic bonding between the single crystal silicon of the first device substrate 10 and the glass of the first lid substrate 40. The bonding between the peripheral portion 19 and the peripheral portion 29 is direct bonding between the single crystal silicon. The peripheral portion 19 is separated from other portions of the first device substrate 10 (such as the movable portions 12A, 12B, the connecting portions 13A, 13B, the bonding portions 14A, 14B, the conductive portions 17A, 17B, and the support portion 18) by a slit that penetrates the silicon substrate F10 in the Z-axis direction.

[0027] Although not shown, the first device substrate 10 further includes a wiring portion for electrically connecting the first device substrate 10 or the second device substrate 20 to the first lid substrate 40 .

[0028] The second device substrate 20 is provided by a silicon substrate F20. The silicon substrate F20 is formed of single crystal silicon. The silicon substrate F20 is formed of, for example, a p-type silicon (Si) semiconductor. The silicon substrate F20 may contain boron (B) or the like as a p-type dopant. The resistance value of the silicon (Si) used in the silicon substrate F20 is, for example, about 10 mΩ·cm. The bonding between the first device substrate 10 and the second device substrate 20 is a direct bonding between the silicon substrate F10 and the silicon substrate F20.

[0029] As shown in FIG. 1 , the second device substrate 20 includes bonding portions 24A and 24B, conductive portions 27A and 27B, a support portion 28, and a peripheral portion 29. The bonding portions 24A and 24B, the conductive portions 27A and 27B, the support portion 28, and the peripheral portion 29 are formed by patterning the silicon substrate F20 through a removal process. The removal process is performed by, for example, DRIE. The removal process may also be performed by other techniques such as wet etching and laser etching. The bonding portions 24A and 24B are collectively referred to as a bonding portion 24. The second device substrate 20 is separated from the second lid substrate 30 in areas overlapping with the movable portion 12, the connecting portion 13, and the bonding portion 14.

[0030] The bonding portion 24A is bonded to the bonding portion 14A of the first device substrate 10. The bonding portion 24B is bonded to the bonding portion 14B of the first device substrate 10. The bonding portions 24A and 24B are spaced apart from the second lid substrate 30. The bonding portion 24A is separated from other portions of the second device substrate 20 (such as the bonding portion 24B, the conductive portions 27A and 27B, the support portion 28, and the peripheral portion 29) by a slit that penetrates the silicon substrate F20 in the Z-axis direction. The bonding portion 24B is separated from other portions of the second device substrate 20 (such as the bonding portion 24A, the conductive portions 27A and 27B, the support portion 28, and the peripheral portion 29) by a slit that penetrates the silicon substrate F20 in the Z-axis direction.

[0031] The conductive portions 27A and 27B electrically connect the first lid substrate 40 and the second device substrate 20 via the first device substrate 10. The conductive portion 27A is bonded to the conductive portion 17A of the first device substrate 10. The conductive portion 17B is bonded to the conductive portion 17B of the first device substrate 10. The conductive portion 27A is separated from other portions of the second device substrate 20 (such as the bonding portions 24A and 24B, the conductive portion 27B, the support portion 28, and the peripheral portion 19) by a slit that penetrates the silicon substrate F20 in the Z-axis direction. The conductive portion 27B is separated from other portions of the first device substrate 10 (such as the bonding portions 24A and 24B, the conductive portion 27A, the support portion 28, and the peripheral portion 19) by a slit that penetrates the silicon substrate F10 in the Z-axis direction.

[0032] The support portion 28 supports the bonding portions 24A and 24B and the conductive portions 27A and 27B of the second device substrate 20. The support portion 28 also functions as a conductive portion that electrically connects the first lid substrate 40 and the second device substrate 20 via the first device substrate 10. The support portion 28 is bonded to the support portion 18 of the first device substrate 10 and to a bonding portion 24 of the second lid substrate 30, which will be described later. The bonding between the support portion 28 and the bonding portion 24 is, for example, a direct bond between the single crystal silicon of the second device substrate 20 and the silicon oxide of the second lid substrate 30. The support portion 28 is separated from other portions of the second device substrate 20 (such as the bonding portions 24A and 24B, the conductive portions 27A and 27B, and the peripheral portion 29) by a slit that penetrates the silicon substrate F20 in the Z-axis direction.

[0033] The peripheral portion 29 is provided in a frame shape along the outer edge of the second device substrate 20. In a plan view, the peripheral portion 29 surrounds the bonding portions 24A and 24B, the conductive portions 27A and 27B, and the support portion 28. The peripheral portion 29 is bonded to the peripheral portion 19 of the first device substrate 10 and to a sidewall 23 of the second lid substrate 30 (described later). The bonding between the peripheral portion 29 and the sidewall 23 is, for example, a direct bond between the single crystal silicon of the peripheral portion 29 and the silicon oxide of the second lid substrate 30. The peripheral portion 29 is separated from other portions of the second device substrate 20 (such as the bonding portions 24A and 24B, the conductive portions 27A and 27B, and the support portion 28) by a slit penetrating the silicon substrate F20 in the Z-axis direction.

[0034] Although not shown, the second device substrate 20 further includes a wiring portion for electrically connecting the second device substrate 20 to the first lid substrate 40 .

[0035] The first lid substrate 40 is provided in a flat plate shape. The first lid substrate 40 is formed of a silicon substrate Q10 and a glass substrate Q11. The silicon substrate Q10 is formed of, for example, a p-type silicon (Si) semiconductor. The resistance value of the silicon (Si) used in the silicon substrate Q10 is, for example, about 10 mΩ·cm. The glass substrate Q11 is formed of a silicon oxide (for example, SiO ２ The glass substrate Q11 is formed of glass containing SiO as a main component. Here, the main component of the glass refers to a component that accounts for 50 mass % or more of all components that make up the glass. As an example, the glass substrate Q11 is formed of glass containing SiO ２ The first lid substrate 40 is formed of silicate glass containing silicon as a main component. The silicon substrates Q10 are provided in multiple regions spaced apart in the XY plane direction. The glass substrate Q11 electrically insulates the multiple silicon substrates Q10 provided in the regions spaced apart in the XY plane direction from each other. Electrodes provided on the first device substrate 10 side of the first lid substrate 40 and external terminals provided on the opposite side from the first device substrate 10 are electrically connected via the silicon substrate Q10. The portion of the first lid substrate 40 that is bonded to the peripheral portion 19 of the first device substrate 10 is provided by the glass substrate Q11.

[0036] The second lid substrate 30 is made up of a silicon substrate P10 and a silicon oxide film P11. The silicon oxide film P11 is provided on the surface of the second lid substrate 30 that is bonded to the second device substrate 20. The silicon substrate P10 of the second lid substrate 30 is bonded to the silicon substrate F20 of the second device substrate 20 via the silicon oxide film P11.

[0037] The second lid substrate 30 has a bottom plate 32, sidewalls 33, and support portions 34. The bottom plate 32 is spaced apart from the bonding portions 24A and 24B and the conductive portions 27A and 27B in the Z-axis direction. The bottom plate 32 is a plate-shaped portion having a main surface extending along the XY plane. The bottom plate 32 is formed of a silicon substrate P10. The sidewalls 33 extend from the outer edge of the bottom plate 32 toward the second device substrate 20. In a plan view, the sidewalls 33 are frame-shaped portions that surround the movable portions 12A and 12B, connecting portions 13A and 13B, bonding portions 14A and 14B, conductive portions 17A and 17B, and support portions 18 of the first device substrate 10. The portions of the sidewalls 33 that connect to the bottom plate 32 are formed of the silicon substrate P10. A silicon oxide film P11 is provided on the surface of the sidewalls 33 that is bonded to the second device substrate 20. A movable space 31 is formed in the second lid substrate 30 in an area that overlaps with the movable portions 12A, 12B, connecting portions 13A, 13B, bonding portions 14A, 14B, and conductive portions 17A, 17B of the first device substrate 10 in a plan view. The movable space 31 is a space surrounded by a bottom plate 32 and sidewalls 33. The support portion 34 extends from the bottom plate 32 toward the support portion 28 of the second device substrate 20. The portion of the support portion 34 that connects to the bottom plate 32 is formed by a silicon substrate P10. A silicon oxide film P11 is provided on the surface of the support portion 34 that is bonded to the second device substrate 20. The support portion 34 sandwiches and fixes the support portions 18, 28 between itself and the first lid substrate 40.

[0038] Next, the configurations of the first device substrate 10 and the second device substrate 20 will be described with reference to FIGS. 2 to 6. FIG. 2 is an enlarged plan view of the interior of the MEMS device 1 according to the first embodiment. FIG. 3 is an enlarged cross-sectional view of the MEMS device 1 taken along line III-III in FIG. 2. FIG. 4 is an enlarged cross-sectional view of the MEMS device 1 taken along line IV-IV in FIG. 2. FIG. 5 is a cross-sectional view of the wiring portions 15 and 25. FIG. 6 is a cross-sectional view of the wiring portions 15 and 25 in a modified example.

[0039] As shown in FIG. 3 , the connecting portion 13 has a trench structure on the second device substrate 20 side. The trench structure of the connecting portion 13 is recessed and opens toward the second device substrate 20 side. The lower surface 13b of the connecting portion 13, which corresponds to the bottom surface of the trench structure, is farther from the upper surface 20a of the second device substrate 20 than the lower surface 12b of the movable portion 12. That is, when the distance in the Z-axis direction between the lower surface 12b of the movable portion 12 and the upper surface 20a of the second device substrate 20 is H1 and the distance in the Z-axis direction between the lower surface 13b of the connecting portion 13 and the upper surface 20a of the second device substrate 20 is H2, the relationship H1<H2 holds. The distance H1 is, for example, 1 μm or more and 3 μm or less. The distance H2 is, for example, 3 μm or more and 5 μm or less. Here, the movable portion 12 whose distance in the Z-axis direction from the upper surface 20a of the second device substrate 20 is H1 is, for example, a portion that does not overlap with the second device substrate 20 in a planar view. The lower surface 13b of the connecting portion 13 is, for example, flat, but is not limited to this and may be a curved surface including an inclined surface.

[0040] 4, the distance in the Z-axis direction between the second device substrate 20 and a portion of the movable part 12 that overlaps with the second device substrate 20 in a plan view is, for example, H2. The portion of the movable part 12 whose distance in the Z-axis direction between it and the second device substrate 20 is H2 is, for example, a portion located between two bonding parts 14 in the direction in which the multiple bonding parts 14 are arranged.

[0041] Furthermore, the portions where the trench structure is provided are not limited to the movable portion 12 and the connecting portion 13. The trench structure may be provided on at least one of the opposing sides of the first device substrate 10 and the second device substrate 20 in the overlapping portions in a plan view of the first device substrate 10 and the second device substrate 20. For example, as shown in FIG. 5 , the second device substrate 20 may have a wiring portion 25 that transmits an electrical signal for detecting capacitance, and the trench structure may be provided in a portion of the first device substrate 10 that faces the wiring portion 25 in the Z-axis direction. The portion where the trench structure is provided facing the wiring portion 25 is, for example, the wiring portion 15 that transmits an electrical signal for detecting capacitance, but is not limited thereto.

[0042] 6, the first device substrate 10 may have a wiring portion 15 that transmits an electrical signal for detecting capacitance, and a trench structure may be provided in a portion of the second device substrate 20 that faces the wiring portion 15 in the Z-axis direction. The portion where the trench structure is provided facing the wiring portion 15 is, for example, a wiring portion 25 that transmits an electrical signal for detecting capacitance, but is not limited to this.

[0043] In addition, when wiring portion 15 and wiring portion 25 intersect in a planar view, a trench structure may be formed in the portion of wiring portion 15 facing wiring portion 25, and a trench structure may be formed in the portion of wiring portion 25 facing wiring portion 15.

[0044] Next, a method for manufacturing the MEMS device 1 according to the first embodiment will be described with reference to Fig. 7 to Fig. 16. Fig. 7 is a flowchart showing the method for manufacturing the MEMS device 1 according to the first embodiment. Figs. 8 to 14 are cross-sectional views showing the manufacturing process of the MEMS device 1. Figs. 15 and 16 are cross-sectional views showing a modified example of the manufacturing process of the MEMS device 1.

[0045] First, a single-crystal silicon substrate is prepared (S10). A planar silicon substrate F10 made of single-crystal silicon is prepared, and its main surface is polished. The main surfaces of the portion intended to become the movable portion 12 (hereinafter referred to as the "intended movable portion 12P"), the portion intended to become the connecting portion 13 (hereinafter referred to as the "intended connecting portion 13P"), and the portion intended to become the bonding portion 14 (hereinafter referred to as the "intended bonding portion 14P") are included in the same plane.

[0046] Next, a trench structure is formed (S20). As shown in Fig. 8, a part of the intended connection portion 13P is removed by dry etching. As a result, a trench structure with a depth H2 is formed in the intended connection portion 13P.

[0047] Next, a recessed structure is formed (S30). The recessed structure is a structure in which the intended movable portion 12P is recessed relative to the intended bonding portion 14P. First, as shown in FIG. 9 , a silicon oxide film ML1 is provided on the silicon substrate F10, and then a silicon nitride film ML2 is provided on the silicon oxide film ML1. Next, the silicon oxide film ML1 and the silicon nitride film ML2 are patterned. The silicon oxide film ML1 and the silicon nitride film ML2 are collectively referred to as a mask MSK. The mask MSK covers the intended connection portion 13P and the intended bonding portion 14P and is open in the intended movable portion 12P. The mask MSK covers the inside of the trench structure. The mask MSK functions as a mask for locally thermally oxidizing the silicon substrate F10. That is, thermal oxidation proceeds in the intended movable portion 12P where the mask MSK is open and the silicon substrate F10 is exposed, while thermal oxidation is limited in the intended connection portion 13P and the intended bonding portion 14P where the silicon substrate F10 is covered by the mask MSK.

[0048] Next, as shown in Figure 10, the silicon substrate F10 is thermally oxidized. Oxygen penetrates the silicon substrate F10 through the openings in the mask MSK and oxidizes the single-crystal silicon to form a thermally oxidized region OX. The thermally oxidized region OX expands over time, starting from the openings in the mask MSK. Because the mask MSK is provided along the trench structure, the thermal oxidation of the silicon substrate F10 progresses in the Z-axis direction, while the progress of thermal oxidation in the X-axis and Y-axis directions is suppressed.

[0049] Next, as shown in FIG. 11 , the mask MSK and the thermal oxidation region OX are removed to obtain a silicon substrate F10 having a recessed structure of depth H1 and a trench structure of depth H2. In this manner, the silicon substrate F10 for the first device substrate 10 is prepared by forming the trench structure and then the recessed structure. Note that depth H1 is the dimension in the Z-axis direction from the lower surface of the intended bonding portion 14P to the lower surface of the intended moving portion 12P, and depth H2 is the dimension in the Z-axis direction from the lower surface of the intended bonding portion 14P to the lower surface of the intended connecting portion 13P. Note that, according to the manufacturing method of the recessed structure of depth H1 using thermal oxidation described above, the depth H1 of the recessed structure can be controlled with high precision, and the electrostatic capacitance formed between the first device substrate 10 and the second device substrate 20 can be set to an appropriate value.

[0050] Next, an etching stopper film ES is provided (S40). First, the etching stopper film ES is provided in the intended movable portion 12P, the intended connection portion 13P, and the intended bonding portion 14P. The etching stopper film ES covers the recessed structure and trench structure of the silicon substrate F10. The etching stopper film ES is, for example, a silicon oxide film formed by thermally oxidizing the silicon substrate F10. The etching stopper film ES may be provided by sputtering, CVD (Chemical Vapor Deposition), or the like. Next, a photoresist film PR is provided on the etching stopper film ES, and the photoresist film PR is patterned. The photoresist film PR covers the intended movable portion 12P and the intended connection portion 13P and has an opening in the intended bonding portion 14P.

[0051] Using the patterned photoresist film PR as a mask, the etching stopper film ES is removed by wet etching. At this time, as shown in Figure 12, the wet etching of the etching stopper film ES proceeds in the Z-axis direction along the trench structure. Therefore, the progress of the wet etching in the X-axis and Y-axis directions in the portions covered with the photoresist film PR is suppressed.

[0052] Next, the second device substrate 20 is directly bonded (S50). First, the second device substrate 20 made of a silicon substrate F20 made of single crystal silicon is prepared. As shown in Fig. 13, the polished surface of the silicon substrate F10 and the polished surface of the silicon substrate F20 are directly bonded.

[0053] Next, the single-crystal silicon substrate is removed (S60). As shown in Figure 13, the silicon substrate F10 is etched by DRIE up to the position where the etching stopper film ES is formed, forming a slit penetrating the silicon substrate F10 in the Z-axis direction. This results in the movable portion 12, connecting portion 13, bonding portion 14, conductive portion 17, support portion 18, and peripheral portion 19. The DRIE is stopped by the etching stopper film ES when it penetrates the silicon substrate F10 in the Z-axis direction.

[0054] Finally, the etching stopper film ES is removed (S70). As shown in Fig. 14, the etching stopper film ES is removed by gaseous hydrofluoric acid gas supplied through the slits provided by DRIE. The gaseous hydrofluoric acid gas diffuses in the X-axis and Y-axis directions through the gap between the first device substrate 10 and the second device substrate 20, efficiently removing the etching stopper film ES.

[0055] The method for forming the etching stopper film ES that opens in the intended bonding portion 14P is not limited to patterning using a photoresist film PR. For example, as shown in FIG. 15 , the etching stopper film ES may be formed so as to fill the recessed structure and trench structure of the silicon substrate F10. The surface of the etching stopper film ES thus formed is planarized by chemical mechanical polishing (CMP). Then, as shown in FIG. 16 , the entire surface of the etching stopper film ES may be wet-etched, and the wet etching may be terminated when the intended bonding portion 14P is exposed, thereby forming the etching stopper film ES that opens in the intended bonding portion 14P.

[0056] Next, the first lid substrate 40 is bonded to the first device substrate 10. Finally, after the silicon substrate F20 is processed to remove the silicon substrate F20, the silicon substrate F20 is directly bonded to the second lid substrate 30. Note that the process of processing the silicon substrate F20 to remove the silicon substrate F20 and the process of directly bonding the silicon substrate F20 to the second lid substrate 30 may be performed between the process of directly bonding the second device substrate 20 (S50) and the process of processing the single crystal silicon substrate to remove the silicon substrate (S60).

[0057] As described above, the MEMS device 1 includes a first device substrate 10 made of single crystal silicon and a second device substrate 20 made of single crystal silicon, and the first device substrate 10 has a bonding portion 14 directly bonded to the second device substrate 20, a movable portion 12 configured to be movable apart from the second device substrate 20, and a connecting portion 13 connecting the movable portion 12 and the bonding portion 14. The connecting portion 13 has a trench structure whose distance to the second device substrate 20 is greater than the distance between the movable portion 12 and the second device substrate 20.

[0058] In this configuration, the first device substrate 10 and the second device substrate 20 are stacked by directly bonding single-crystal silicon together. This reduces warping of the MEMS structure compared to when the MEMS structure is formed using polycrystalline silicon, which has a higher stress than single-crystal silicon. This allows for improved performance of the MEMS device 1. Furthermore, the first device substrate 10 and the second device substrate 20 can be bonded together while a gap is formed between them. Therefore, without providing multiple through-holes in the first device substrate 10 for supplying etching gas to remove the etching stopper film ES, etching gas can be supplied through slits forming the movable portion 12 and the like, and the etching gas can be diffused into the gap between the first device substrate 10 and the second device substrate 20. Therefore, the elimination of multiple through-holes for supplying etching gas allows for a more compact and dense MEMS structure, thereby improving the performance of the MEMS device 1.

[0059] By providing the connecting portion 13 with a trench structure, for example, when thermally oxidizing the first device substrate 10, the trench structure can stop the progression of thermal oxidation in the X-axis or Y-axis direction. Furthermore, when patterning the etching stopper film ES, the trench structure can stop the progression of removal processing of the etching stopper film ES in the X-axis or Y-axis direction. That is, the positional accuracy of the end of the etching stopper film ES in the X-axis or Y-axis direction can be improved. Therefore, single-crystal silicon substrates can be directly bonded together with the etching stopper film ES extended close to the bonding portion 14 in the X-axis or Y-axis direction. As a result, the dimensions of the connecting portion 13 in the X-axis or Y-axis direction can be reduced, and the movable portion 12 can be located close to the bonding portion 14. Furthermore, the distance between adjacent bonding portions 14 can be reduced. As a result, the MEMS structure can be miniaturized and highly dense, thereby improving the performance of the MEMS device 1.

[0060] In one aspect of the above, the first device substrate 10 further has a first wiring portion 15 for detecting capacitance, and the first wiring portion 15 has a trench structure in which the distance between it and the second device substrate 20 is greater than the distance between the movable portion 12 and the second device substrate 20.

[0061] This makes it possible to reduce the parasitic capacitance formed between the first wiring section 15 and the second device substrate 20 .

[0062] In one aspect of the above, the second device substrate 20 has a second wiring portion 25 for detecting capacitance, and the second wiring portion 25 has a trench structure in which the distance between it and the first device substrate 10 is greater than the distance between the movable portion 12 and the second device substrate 20.

[0063] This makes it possible to reduce the parasitic capacitance formed between the second wiring portion 25 and the first device substrate 10 .

[0064] In one aspect of the above, the capacitance between the first device substrate 10 and the first lid substrate 40 and the capacitance between the first device substrate 10 and the second device substrate 20 are detected.

[0065] This allows for improved detection accuracy compared to a configuration that detects only the capacitance between the first device substrate 10 and the first lid substrate 40, or a configuration that detects only the capacitance between the first device substrate 10 and the second device substrate 20.

[0066] In one aspect of the above, the second device substrate 20 is spaced apart from the second lid substrate 30 in the region where it overlaps with the movable portion 12 of the first device substrate 10 .

[0067] This makes it possible to suppress the propagation of stress from the second lid substrate 30 to the first device substrate 10 and the second device substrate 20. Therefore, it is possible to suppress false detection when detecting inertial forces and the like by eliminating the influence of external stress.

[0068] As described above, the manufacturing method of the MEMS device 1 includes preparing a first device substrate 10 made of single crystal silicon, preparing a second device substrate 20 made of single crystal silicon, and directly bonding the first device substrate 10 and the second device substrate 20. Preparing the first device substrate 10 includes preparing a single crystal silicon substrate F10, forming a recessed structure in which the portion that will become the movable portion 12 is recessed relative to the portion that will become the bonding portion 14, and forming a trench structure that is deeper than the recessed structure in the portion that will become the connecting portion 13.

[0069] This stacking of the first device substrate 10 and the second device substrate 20 by directly bonding single-crystal silicon substrates together suppresses warping of the MEMS structure compared to when the MEMS structure is formed using polycrystalline silicon, which has a higher stress than single-crystal silicon. This improves the performance of the MEMS device 1. Furthermore, the first device substrate 10 and the second device substrate 20 can be bonded together while a gap is formed between them. Therefore, without providing multiple through-holes in the first device substrate 10 for supplying etching gas to remove the etching stopper film ES, etching gas can be supplied through slits forming the movable portion 12 and the like, and the etching gas can be diffused into the gap between the first device substrate 10 and the second device substrate 20. Therefore, by eliminating the multiple through-holes for supplying etching gas, the MEMS structure can be miniaturized and densified, thereby improving the performance of the MEMS device 1.

[0070] By providing the connecting portion 13 with a trench structure, for example, when thermally oxidizing the first device substrate 10, the trench structure can stop the progression of thermal oxidation in the X-axis or Y-axis direction. Furthermore, when patterning the etching stopper film ES, the trench structure can stop the progression of removal processing of the etching stopper film ES in the X-axis or Y-axis direction. That is, the positional accuracy of the end of the etching stopper film ES in the X-axis or Y-axis direction can be improved. Therefore, single-crystal silicon substrates can be directly bonded together with the etching stopper film ES extended close to the bonding portion 14 in the X-axis or Y-axis direction. As a result, the dimensions of the connecting portion 13 in the X-axis or Y-axis direction can be reduced, and the movable portion 12 can be located close to the bonding portion 14. Furthermore, the distance between adjacent bonding portions 14 can be reduced. As a result, the MEMS structure can be miniaturized and highly dense, thereby improving the performance of the MEMS device 1.

[0071] Other embodiments will be described below. Components that are the same as or similar to those in the first embodiment are denoted by the same or similar reference numerals, and descriptions thereof will be omitted as appropriate. Furthermore, similar effects resulting from similar components will not be mentioned in detail.

[0072] Second Embodiment Next, the structure of a MEMS device 2 according to a second embodiment will be described with reference to Fig. 17. Fig. 17 is an enlarged cross-sectional view of the MEMS device according to the second embodiment.

[0073] A lower surface 213b, which corresponds to the bottom surface of the trench structure provided in the connecting portion 213 of the first device substrate 210, is provided as an inclined surface that moves away from the second device substrate 20 as it moves from the bonding portion 14 toward the movable portion 12. In other words, the distance H2 in the Z-axis direction between the lower surface 213b of the connecting portion 213 and the upper surface 20a of the second device substrate 20 is minimum at a position close to the bonding portion 14 and maximum at a position close to the movable portion 12. When the minimum value of the distance H2 is H2min and the maximum value of the distance H2 is H2max, the relationship H1<H2min<H2max holds. However, as long as the relationship H1<H2max holds, the relationship H2min≦H1 may also hold.

[0074] Next, a method for manufacturing the MEMS device 2 according to the second embodiment will be described with reference to Figures 18 to 21. Figures 18 to 21 are cross-sectional views showing the manufacturing process of the MEMS device 2.

[0075] The manufacturing method of the MEMS device 2 differs from the manufacturing method of the MEMS device 1 in that a trench structure is formed after a recessed structure is formed. First, as shown in FIG. 18 , a double-side polished single-crystal silicon substrate F10 is prepared. A silicon nitride film ML21 is formed on the silicon substrate F10, a silicon oxide film ML22 is formed on the silicon nitride film ML21, and a silicon nitride film ML23 is formed on the silicon oxide film ML22. Next, the silicon nitride film ML21, the silicon oxide film ML22, and the silicon nitride film ML23 are patterned. The silicon nitride film ML21, the silicon oxide film ML22, and the silicon nitride film ML23 are collectively referred to as a mask MSK2. The mask MSK2 covers the intended bonding portion 14P and the intended connection portion 213P and has an opening in the intended movable portion 12P.

[0076] 19, the silicon substrate F10 is locally thermally oxidized. The thermally oxidized region OX starts from the edge of the mask MSK2 and spreads to the portion covered by the mask MSK2. As a result, an inclined surface is formed in the intended coupling portion 213P of the silicon substrate F10.

[0077] Next, as shown in FIG. 20 , the mask MSK2 and the thermally oxidized region OX are removed to obtain a silicon substrate F10 having a recessed structure with a depth H1. Next, as shown in FIG. 21 , the inclined surface formed on the silicon substrate F10 is removed by dry etching to form a trench structure with a depth H2. In the example shown in FIG. 21 , the dimensions of the opening of the mask for dry etching (hereinafter referred to as the "dry etching region") are larger than the dimensions of the inclined surface in a planar view. Furthermore, in a planar view, the center of the dry etching region overlaps with the center of the inclined surface. Therefore, a surface parallel to the main surface of the intended bonding portion 14P is formed on the inclined surface of the intended connection portion 213P toward the intended bonding portion 14P, where the depth H2 of the trench structure is H2min. Furthermore, a surface parallel to the main surface of the intended movable portion 12P is formed on the inclined surface of the intended connection portion 213P toward the intended movable portion 12P, where the depth H2 of the trench structure is H2max. In this manner, a recessed structure is formed in the single crystal silicon substrate, and then a trench structure is formed, thereby preparing a silicon substrate F10 for the first device substrate 210.

[0078] If H1<H2max is satisfied, the dimensions of the dry etching region may be the same as or smaller than the dimensions of the inclined surface in a plan view. Furthermore, the center of the dry etching region may be positioned closer to the intended joining portion 14P from the center of the inclined surface, or may be positioned closer to the intended movable portion 12P from the center of the inclined surface in a plan view.

[0079] Some or all of the embodiments of the present invention will be described below, but the present invention is not limited to the following descriptions.

[0080] <1> A MEMS device comprising a first device substrate made of single crystal silicon and a second device substrate made of single crystal silicon, detecting capacitance formed by the first device substrate, wherein the first device substrate has: a bonding portion directly bonded to the second device substrate; a movable portion configured to be movable and spaced apart from the second device substrate; and a connecting portion connecting the bonding portion and the movable portion, wherein the connecting portion is provided with a trench structure whose distance to the second device substrate is greater than the distance between the movable portion and the second device substrate.

[0081] <2> The MEMS device according to <1>, wherein the first device substrate further includes a first wiring portion for detecting capacitance, and the first wiring portion is provided with a trench structure whose distance to the second device substrate is greater than the distance between the movable portion and the second device substrate.

[0082] <3> The MEMS device according to <1> or <2>, wherein the second device substrate has a second wiring portion for detecting capacitance, and the second wiring portion has a trench structure in which the distance between the second wiring portion and the first device substrate is greater than the distance between the movable portion and the second device substrate.

[0083] <4> The MEMS device according to any one of <1> to <3>, wherein the distance between the movable portion and the second device substrate is 1 μm or more and 3 μm or less.

[0084] <5> The MEMS device according to any one of <1> to <4>, wherein a distance between the trench structure of the coupling portion and the second device substrate is 3 μm or more and 5 μm or less.

[0085] <6> The MEMS device according to any one of <1> to <5>, further including: a first lid substrate provided on the first device substrate opposite to the second device substrate; and a second lid substrate provided on the second device substrate opposite to the first device substrate.

[0086] <7> The MEMS device according to <6>, wherein the movable portion of the first device substrate is separated from the first lid substrate, and a capacitance between the first device substrate and the first lid substrate and a capacitance between the first device substrate and the second device substrate are detected.

[0087] <8> The MEMS device according to <6> or <7>, wherein the second device substrate is separated from the second lid substrate in a region overlapping with the movable portion.

[0088] <9> A method for manufacturing a MEMS device that detects capacitance formed by a first device substrate, the method including: preparing a first device substrate made of single crystal silicon; preparing a second device substrate made of single crystal silicon; and directly bonding the first device substrate and the second device substrate, wherein preparing the first device substrate includes: preparing a single crystal silicon substrate; and forming a recessed structure in which a portion that becomes a movable portion is recessed relative to a portion that becomes a joint; and forming a trench structure that is deeper than the recessed structure in a portion that becomes a connecting portion that connects the joint and the movable portion.

[0089] <10> The method for manufacturing a MEMS device according to <9>, wherein the trench structure is formed by dry etching the single-crystal silicon substrate.

[0090] <11> The method for manufacturing a MEMS device according to <9> or <10>, wherein the recessed structure is formed by partially thermally oxidizing the single-crystal silicon substrate and removing the thermally oxidized region.

[0091] <12> The method for manufacturing a MEMS device according to any one of <9> to <11>, wherein a trench structure is formed after forming the recessed structure.

[0092] <13> The method for manufacturing a MEMS device according to any one of <9> to <11>, wherein the recessed structure is formed after the trench structure is formed.

[0093] The embodiments of the present invention are not particularly limited and can be appropriately applied to any sensor that detects changes in capacitance, such as an inertial sensor such as an acceleration sensor or a gyro sensor, or a pressure sensor.

[0094] As described above, according to one aspect of the present invention, it is possible to provide a MEMS device that can achieve high performance and a method for manufacturing the same.

[0095] The above-described embodiments are intended to facilitate understanding of the present invention and are not intended to limit the present invention. The present invention may be modified or improved without departing from its spirit, and such modifications and improvements are also included within the scope of the present invention. In other words, designs modified by those skilled in the art as appropriate are also encompassed within the scope of the present invention as long as they incorporate the characteristics of the present invention. For example, the elements of the present embodiments, as well as their arrangement, materials, conditions, shapes, sizes, etc., are not limited to those exemplified and can be modified as appropriate. Furthermore, the elements of the present embodiments can be combined to the extent technically possible, and such combinations are also encompassed within the scope of the present invention as long as they incorporate the characteristics of the present invention.

[0096] DESCRIPTION OF SYMBOLS 1...MEMS device 10...first device substrate 11A, 11B...movable space 12A, 12B, 12...movable part 13A, 13...connecting part 14A, 14B, 14...joint part 12b, 13b, 14b...lower surface 17A, 17B...conductive part 18...support part 19...periphery part 20...second device substrate 20a...upper surface 24A, 24B, 24...joint part 25...wiring part 27A, 27B...conductive part 28...support part 29...periphery part 40...first lid substrate 30...second lid substrate 31...movable space 32...bottom plate 33...side wall 34...support part P10, Q10, F10, F20...silicon substrate P11...silicon oxide film Q11...glass substrate

Claims

1. A MEMS device comprising a first device substrate made of single crystal silicon and a second device substrate made of single crystal silicon, detecting electrostatic capacitance formed by the first device substrate, wherein the first device substrate has: a bonding portion directly bonded to the second device substrate; a movable portion configured to be movable at a distance from the second device substrate; and a connecting portion connecting the bonding portion and the movable portion, wherein the connecting portion is provided with a trench structure whose distance to the second device substrate is greater than the distance between the movable portion and the second device substrate.

2. The MEMS device according to claim 1, wherein the first device substrate further has a first wiring section for detecting capacitance, and the first wiring section is provided with a trench structure whose distance to the second device substrate is greater than the distance between the movable section and the second device substrate.

3. A MEMS device according to claim 1 or 2, wherein the second device substrate has a second wiring section for detecting capacitance, and the second wiring section has a trench structure in which the distance between the second wiring section and the first device substrate is greater than the distance between the movable section and the second device substrate.

4. The MEMS device according to any one of claims 1 to 3, wherein the distance between the movable portion and the second device substrate is 1 μm or more and 3 μm or less.

5. The MEMS device according to any one of claims 1 to 4, wherein the distance between the trench structure of the connecting portion and the second device substrate is 3 µm or more and 5 µm or less.

6. A MEMS device according to any one of claims 1 to 5, further comprising: a first lid substrate provided on the side of the first device substrate opposite the second device substrate; and a second lid substrate provided on the side of the second device substrate opposite the first device substrate.

7. The MEMS device according to claim 6, wherein the movable portion of the first device substrate is spaced apart from the first lid substrate, and a capacitance between the first device substrate and the first lid substrate and a capacitance between the first device substrate and the second device substrate are detected.

8. The MEMS device according to claim 6 or 7, wherein the second device substrate is spaced apart from the second lid substrate in a region overlapping with the movable portion.

9. A method for manufacturing a MEMS device that detects electrostatic capacitance formed by the first device substrate, the method comprising: preparing a first device substrate made of single crystal silicon; preparing a second device substrate made of single crystal silicon; and directly bonding the first device substrate and the second device substrate, wherein preparing the first device substrate comprises: preparing a single crystal silicon substrate; forming a recessed structure in which a portion that will become a movable portion is recessed relative to a portion that will become a joint; and forming a trench structure that is deeper than the recessed structure in a portion that will become a connecting portion that connects the joint and the movable portion.

10. The method for manufacturing a MEMS device according to claim 9, wherein the trench structure is formed by dry etching the single crystal silicon substrate.

11. The method for manufacturing a MEMS device according to claim 9 or 10, wherein the recessed structure is formed by partially thermally oxidizing the single crystal silicon substrate and removing the thermally oxidized region.

12. The method for manufacturing a MEMS device according to any one of claims 9 to 11, wherein the trench structure is formed after the recessed structure is formed.

13. The method for manufacturing a MEMS device according to any one of claims 9 to 11, wherein the recessed structure is formed after the trench structure is formed.

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