sensor

Abstract

To provide a sensor capable of obtaining high detection sensitivity.SOLUTION: According to the embodiment, a sensor includes a substrate, a fixed electrode, a first fixed section, a first support section, and a movable section. The substrate includes a first area and a second area. The fixed electrode is fixed to the first area. The first fixed section is fixed to the second area. The first support section is connected to the first fixed section. The first support section includes a first support layer, a first layer, and a second layer. The first layer is provided between the first support layer and at least one portion of the second layer in a first direction from the first support layer to the second layer. The first layer contains a first element containing at least one selected from a group comprising Pt, Pd, and Ti, and oxygen. The second layer contains a second element different from the first element, and oxygen. The movable section is supported by the first support section. A first gap is provided between the fixed electrode and the movable section.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] Embodiments of the present invention relate to sensors.

Background Art

[0002] For example, there are sensors that apply MEMS structures. In sensors, high detection sensitivity is desired.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Embodiments of the present invention provide a sensor capable of obtaining high detection sensitivity.

Means for Solving the Problems

[0005] According to an embodiment of the present invention, a sensor includes a substrate, a fixed electrode, a first fixing portion, a first support portion, and a movable portion. The substrate includes a first region and a second region. The fixed electrode is fixed to the first region. The first fixing portion is fixed to the second region. The first support portion is connected to the first fixing portion. The first support portion includes a first support layer, a first layer, and a second layer. In a first direction from the first support layer to the second layer, the first layer is provided between at least a part of the first support layer and the second layer. The first layer includes at least one first element selected from the group consisting of Pt, Pd, and Ti, and oxygen. The second layer includes a second element different from the first element and oxygen. The movable portion is supported by the first support portion. A first gap is provided between the fixed electrode and the movable portion.

Brief Description of the Drawings

[0006] [Figure 1] Figure 1 is a schematic cross-sectional view illustrating a sensor according to the first embodiment. [Figure 2] Figure 2 is a graph illustrating the characteristics of the sensor. [Figure 3] Figures 3(a) and 3(b) are schematic cross-sectional views illustrating the operation of the sensor according to the first embodiment. [Figure 4] Figure 4 is a schematic cross-sectional view illustrating a part of the sensor according to the first embodiment. [Figure 5] Figure 5 is a schematic cross-sectional view illustrating a part of the sensor according to the first embodiment. [Modes for carrying out the invention]

[0007] Embodiments of the present invention will be described below with reference to the drawings. Drawings are schematic or conceptual, and the relationships between the thickness and width of each part, as well as the ratios of the sizes of different parts, are not necessarily identical to those of reality. Even when representing the same part, the dimensions and ratios may differ between drawings. In this specification and in each figure, elements similar to those described above are denoted by the same reference numerals with respect to previously shown figures, and detailed explanations are omitted as appropriate.

[0008] (First Embodiment) Figure 1 is a schematic cross-sectional view illustrating a sensor according to the first embodiment. As shown in Figure 1, the sensor 110 according to this embodiment includes a base 40, a fixed electrode 55, a first fixed part 21, a first support part 31s, and a movable part 30M.

[0009] The substrate 40 includes a first region 41 and a second region 42. The substrate 40 may be, for example, a silicon substrate.

[0010] The fixed electrode 55 is fixed to the first region 41. An insulating film 55a may be provided on the fixed electrode 55.

[0011] The first fixing portion 21 is fixed to the second region 42. The first support portion 31s is connected to the first fixing portion 21. The first support portion 31s includes a first support layer 31L, a first layer 31, and a second layer 32. The first layer 31 is fixed to the first support layer 31L. In a first direction D1 from the first support layer 31L to the second layer 32, the first layer 31 is provided between the first support layer 31L and at least a portion of the second layer 32.

[0012] The first layer 31 comprises a first element including at least one selected from the group consisting of Pt, Pd, and Ti, and oxygen. For example, the first layer 31 comprises an oxide of the first element. For example, the first layer 31 comprises a bond between the first element and oxygen.

[0013] The second layer 32 contains a second element different from the first element, and oxygen. In one example, the second element includes at least one selected from the group consisting of Si and Al. For example, the second layer 32 contains an oxide of the second element. For example, the second layer 32 contains a bond between the second element and oxygen.

[0014] The movable part 30M is supported by the first support part 31s. A first gap G1 is provided between the fixed electrode 55 and the movable part 30M.

[0015] For example, the first layer 31 is reduced by the target gas around the first support portion 31s. At least a portion of the oxide of the first element contained in the first layer 31 is reduced. The target gas includes, for example, hydrogen. When the first layer 31 is reduced, for example, oxygen contained in the first layer 31 is released from the first layer 31. The structure of the first layer 31 changes. For example, the volume of the first layer 31 changes.

[0016] A change in the structure of the first layer 31 generates stress between the first layer 31 and the first support layer 31L. This stress is, for example, tensile stress. For example, the first layer 31 tries to contract relative to the first support layer 31L. This changes the shape of the first support part 31s. This change in shape changes the distance between the movable part 30M and the fixed electrode 55. The capacitance changes in accordance with the change in distance. By detecting the change in capacitance, the target gas can be detected.

[0017] In an embodiment, the above-described second layer 32 is provided. As a result, it has been found that higher detection sensitivity can be obtained.

[0018] FIG. 2 is a graph illustrating the characteristics of the sensor. The horizontal axis in FIG. 2 is the concentration parameter CP1. The concentration parameter CP1 is the square root of the concentration of the gas to be detected. An increase in the concentration parameter CP1 corresponds to an increase in the concentration of the gas to be detected. The vertical axis is the change in capacitance ΔC. The change ΔC is based on the capacitance when the concentration of the gas to be detected is zero. A negative change ΔC corresponds to a decrease in capacitance.

[0019] FIG. 2 shows the characteristics of the sensor 110 according to the embodiment and the characteristics of the sensor 119 of the first reference example.

[0020] As shown in FIG. 2, when the concentration parameter CP1 increases, the change in capacitance ΔC is negative, and the absolute value of the change ΔC increases. That is, when the concentration of the gas to be detected increases, the capacitance decreases.

[0021] As shown in FIG. 2, in the sensor 110, the ratio (slope) of the change in ΔC with respect to the change in the concentration parameter CP1 is higher than the ratio (slope) in the sensor 119. In the sensor 110, the object to be detected can be detected with high sensitivity.

[0022] Around the first support portion 31s, in addition to the gas to be detected (e.g., a reducing gas), oxygen present in the air exists. In the first reference example in which the second layer 32 is not provided, it is considered that oxygen adsorbs to the first layer 31. In the first reference example, it is considered that the reduction of the first layer 31 (the first element) and the desorption of the oxygen adsorbed to the first layer 31 occur simultaneously. The change in stress in the first support portion 31s with respect to these phenomena is in the reverse direction. Therefore, in the first reference example, it is difficult to sufficiently increase the sensitivity.

[0023] In contrast, the presence of the second layer 32 suppresses the influence of oxygen on the first layer 31. As a result, it is believed that high detection sensitivity can be obtained in this embodiment.

[0024] Figures 3(a) and 3(b) are schematic cross-sectional views illustrating the operation of the sensor according to the first embodiment. In the second state ST2 shown in Figure 3(a), the concentration of the target gas (e.g., hydrogen) is low. In the second state ST2, the target gas (e.g., hydrogen) is substantially absent. In the first state ST1 shown in Figure 3(b), the target gas (e.g., hydrogen) is present. In the first state ST1, the concentration of the target gas (e.g., hydrogen) is higher than the concentration in the second state ST2.

[0025] As shown in Figure 3(a), in the second state ST2, the first layer 31 contains an oxide 31MO of the first element (e.g., Pt oxide). Oxygen 81O from the air is adsorbed on the surface of the second layer 32.

[0026] As shown in Figure 3(b), in the first state ST1, the target gas 81H (e.g., hydrogen) passes through the second layer 32 and reaches the first layer 31. Reduction of the first element occurs in the first layer 31. The target gas 81H is in a molecular state (hydrogen molecule) on the surface of the second layer 32. Therefore, there is virtually no effect on the oxygen adsorbed on the surface of the second layer 32. As a result, oxygen detachment is suppressed. In this embodiment, by suppressing oxygen detachment, the changes due to reduction are efficiently utilized. According to this embodiment, a sensor with high detection sensitivity can be provided.

[0027] In this embodiment, the desorption of adsorbed oxygen is suppressed while the reduction of the first element oxide occurs. This allows for a highly sensitive response to even minute changes in the target substance in the atmosphere (e.g., hydrogen). For example, an ultra-high sensitivity hydrogen sensor can be obtained.

[0028] For example, layer 2 32 does not contain element 1, or the concentration of element 1 in layer 2 32 is lower than the concentration of element 1 in layer 1 31.

[0029] For example, the first layer 31 does not contain the second element, or the concentration of the second element in the first layer 31 is lower than the concentration of the second element in the second layer 32.

[0030] For example, element 1 can be reduced by the target gas. Element 2 is not substantially reduced by the target gas. In one example, the target gas is hydrogen.

[0031] As shown in Figure 1, the movable part 30M may include a movable electrode 35. The capacitance may be the capacitance between the fixed electrode 55 and the movable electrode 35.

[0032] As shown in Figure 2, the concentration of the target gas in the first state ST1 (high concentration) is higher than the concentration of the target gas in the second state ST2 (low concentration). The first capacitance between the fixed electrode 55 and the movable part 30M in the first state ST1 is smaller than the second capacitance between the fixed electrode 55 and the movable part 30M in the second state ST2.

[0033] Thus, changes in electrical capacitance correspond to the concentration of the target gas. By detecting changes in electrical capacitance, the target gas can be detected. For example, the target gas can be detected with high sensitivity, ranging from approximately 0.1 ppm to 1000 ppm.

[0034] As shown in Figure 1, the sensor 110 may further include a control unit 70. The control unit 70 is capable of detecting electrical capacitances (e.g., a first electrical capacitance and a second electrical capacitance).

[0035] The change in capacitance corresponds to the change in the distance dz between the fixed electrode 55 and the movable part 30M (movable electrode 35). For example, the first distance between the fixed electrode 55 and the movable part 30M in the first state ST1 (high concentration) is longer than the second distance between the fixed electrode 55 and the movable part 30M in the second state ST2 (low concentration).

[0036] For example, a change in distance dz may be detected. For example, the displacement of the movable part 30M may be detected by optical methods or the like.

[0037] As described above, the change in distance dz may be based on the stress resulting from the change in the volume of the first layer 31. For example, the first volume of the first layer 31 in the first state ST1 (high concentration) is smaller than the second volume of the first layer 31 in the second state ST2 (low concentration).

[0038] As shown in Figure 1, in this example, the first support layer 31L is provided between the base 40 and the first layer 31. A second void G2 is provided between the base 40 and the first support layer 31L.

[0039] In this example, the sensor 110 further includes a first connection portion 31c. A portion of the first connection portion 31c is connected to a first support portion 31s. Another portion of the first connection portion 31c is connected to a movable portion 30M. A third gap G3 is provided between the base 40 and the first connection portion 31c. For example, the first connection portion 31c may have a meander structure.

[0040] As shown in Figure 1, the sensor 110 may include a second fixing portion 22 and a second support portion 32s. The base 40 further includes a third region 43. The first region 41 is located between the second region 42 and the third region 43. The second fixing portion 22 is fixed to the third region 43. The second support portion 32s is connected to the second fixing portion 22. The second support portion 32s includes a second support layer 32L, a third layer 33, and a fourth layer 34. The third layer 33 is fixed to the second support layer 32L. At least a portion of the third layer 33 is provided between the second support layer 32L and the fourth layer 34.

[0041] The third layer 33 contains the first element and oxygen. The fourth layer 34 contains the second element and oxygen. The third layer 33 contains, for example, an oxide of the first element. The third layer 33 contains, for example, a bond between the first element and oxygen. The fourth layer 34 contains, for example, an oxide of the second element. The fourth layer 34 contains, for example, a bond between the second element and oxygen.

[0042] For example, layer 4 34 does not contain element 1. Or, the concentration of element 1 in layer 4 34 is lower than the concentration of element 1 in layer 33.

[0043] For example, layer 33 does not contain element 2, or the concentration of element 2 in layer 33 is lower than the concentration of element 2 in layer 44.

[0044] The movable part 30M is provided between the first support part 31s and the second support part 32s. The movable part 30M is supported by the first support part 31s and the second support part 32s. A fourth gap G4 is provided between the base body 40 and the second support part 32s. A cantilever beam type structure may be applied.

[0045] In this example, the sensor 110 further includes a second connection portion 32c. A portion of the second connection portion 32c is connected to a second support portion 32s. Another portion of the second connection portion 32c is connected to a movable portion 30M. A fifth gap G5 is provided between the base 40 and the second connection portion 32c. The second connection portion 32c has, for example, a meander structure.

[0046] As shown in Figure 1, the first support portion 31s may include a first conductive member 31h. The second support portion 32s may include a second conductive member 32h. For example, the temperature of the first support portion 31s can be increased by an electric current flowing through the first conductive member 31h. For example, the temperature of the second support portion 32s can be increased by an electric current flowing through the second conductive member 32h. For example, by heating the support portion, various substances (including hydrogen, for example) adsorbed on the first support portion 31s and the second support portion 32s can be released.

[0047] The thicknesses of the first layer 31 and the third layer 33 are, for example, 1 nm to 1 μm. The thicknesses of the second layer 32 and the fourth layer 34 are, for example, 0.1 nm to 1 μm. The thicknesses of the first support layer 31L and the second support layer 32L are, for example, 10 nm to 10 μm. The thicknesses correspond to the length along the first direction D1.

[0048] The first support layer 31L and the second support layer 32L each contain, for example, at least one selected from the group consisting of nitrogen and oxygen, and silicon. The first support layer 31L and the second support layer 32L may also contain silicon nitride or silicon oxide.

[0049] Figures 4 and 5 are schematic cross-sectional views illustrating a part of the sensor according to the first embodiment. These figures illustrate the first support portion 31s. As shown in Figures 4 and 5, in the sensor 111 and sensor 112 according to this embodiment, the configuration of the first support portion 31s differs from that of the sensor 110. The configurations of the sensor 111 and sensor 112 other than the first support portion 31s may be the same as those of the sensor 110.

[0050] As shown in Figure 4, in the sensor 111, the first layer 31 is provided between multiple regions included in the second layer 32 in a direction intersecting the first direction D1. For example, the upper surface of the first layer 31 is covered by the second layer 32. The sides of the first layer 31 may be covered by the second layer 32. The effects of oxygen are more effectively suppressed in the first layer 31.

[0051] As shown in Figure 5, in the sensor 112, at least a portion of the first support layer 31L is provided between a portion of the second layer and the first layer 31 in the first direction D1. For example, in the first direction D1, the first support layer 31L and the first layer 31 may be provided between multiple regions included in the second layer 32.

[0052] In sensors 111 and 112, the configuration of the first support portion 31s may be applied to the second support portion 32s.

[0053] There are resistive and semiconductor type hydrogen sensors. However, there are limitations to reducing power consumption in these hydrogen sensors.

[0054] In this embodiment, for example, the first layer 31 is reduced by the target gas (hydrogen). As a result, the first support portion 31s, which includes the first layer 31, deforms. This deformation of the first support portion 31s is detected, for example, as a change in electrical capacitance.

[0055] In this embodiment, the first layer 31 (sensitive film) contains a metal oxide. The metal oxide has catalytic properties. When a reducing gas such as hydrogen approaches the sensitive film, the film stress changes in the direction of the tensile stress. The concentration of oxygen in the sensitive film changes depending on the concentration (including presence or absence) of the target gas to be detected.

[0056] For example, when a reducing gas such as hydrogen approaches the sensitive film, hydrogen molecules dissociate into hydrogen atoms at the film surface. These hydrogen atoms reduce metal oxides, forming water and detaching. The frequency of this reaction depends on the hydrogen concentration. When the amount of oxygen in the sensitive film decreases, the film stress changes in the tensile direction.

[0057] In this embodiment, for example, the reducing action of a catalytic metal oxide is utilized. For instance, the metal oxide is reduced by the reducing gas to be detected. This changes the volume of the layer containing the catalyst metal. This change in volume is detected as a change in capacitance. By utilizing the reducing action, even extremely small concentrations of reducing gas, such as 0.1 ppm, can be detected with high sensitivity.

[0058] The embodiments may include the following technical proposals. (Technical proposal 1) A substrate including a first region and a second region, A fixed electrode fixed in the first region, The first fixing part fixed to the second region, A first support portion connected to the first fixed portion, the first support portion comprising a first support layer, a first layer, and a second layer, wherein in a first direction from the first support layer to the second layer, the first layer is provided between the first support layer and at least a portion of the second layer, the first layer comprising a first element including at least one selected from the group consisting of Pt, Pd, and Ti, and oxygen, and the second layer comprising a second element different from the first element, and oxygen, the first support portion, A movable part supported by the first support part, wherein a first gap is provided between the fixed electrode and the movable part, A sensor equipped with this feature.

[0059] (Technical proposal 2) The sensor according to Technical Proposal 1, wherein the second element comprises at least one selected from the group consisting of Si and Al.

[0060] (Technical proposal 3) The sensor according to Technical Proposal 1 or 2, wherein the second layer does not contain the first element, or the concentration of the first element in the second layer is lower than the concentration of the first element in the first layer.

[0061] (Technical proposal 4) The sensor according to Technical Proposal 3, wherein the first layer does not contain the second element, or the concentration of the second element in the first layer is lower than the concentration of the second element in the second layer.

[0062] (Technical proposal 5) The sensor according to any one of Technical Proposals 1 to 4, wherein the first layer is provided between a plurality of regions included in the second layer in a direction intersecting the first direction.

[0063] (Technical proposal 6) At least a portion of the first support layer is provided between a portion of the second layer and the first layer in a first direction, the sensor according to any one of Technical Proposals 1 to 5.

[0064] (Technical proposal 7) The sensor according to any one of the technical proposals 1 to 6, wherein the first layer is reduced by the target gas around the first support portion.

[0065] (Technical proposal 8) The sensor described in Technical Proposal 7 contains hydrogen as the target gas for detection.

[0066] (Technical proposal 9) The concentration of the target gas in the first state is higher than the concentration of the target gas in the second state. The sensor according to any one of Technical Proposals 1 to 6, wherein the first distance between the fixed electrode and the movable part in the first state is longer than the second distance between the fixed electrode and the movable part in the second state.

[0067] (Technical proposal 10) The concentration of the target gas in the first state is higher than the concentration of the target gas in the second state. The sensor according to any one of Technical Proposals 1 to 6, wherein the first volume of the first layer in the first state is smaller than the second volume of the first layer in the second state.

[0068] (Technical proposal 11) The concentration of the target gas in the first state is higher than the concentration of the target gas in the second state. The sensor according to any one of Technical Proposals 1 to 6, wherein the first capacitance between the fixed electrode and the movable part in the first state is smaller than the second capacitance between the fixed electrode and the movable part in the second state.

[0069] (Technical proposal 12) The sensor according to technical proposal 11, further comprising a control unit capable of detecting the first capacitance and the second capacitance.

[0070] (Technical proposal 13) The first layer comprises a bond between the first element and oxygen, The sensor according to any one of Technical Proposals 1 to 12, wherein the second layer includes a bond between the second element and oxygen.

[0071] (Technical proposal 14) The first support portion further includes a first conductive member, The sensor according to any one of Technical Proposals 1 to 13, wherein the temperature of the first support portion can be raised by the current flowing through the first conductive member.

[0072] (Technical proposal 15) The first support layer comprises at least one selected from the group consisting of nitrogen and oxygen, and silicon, according to any one of the technical proposals 1 to 14.

[0073] (Technical proposal 16) The first support layer is provided between the substrate and the first layer. A sensor according to any one of the technical proposals 1 to 15, wherein a second void is provided between the substrate and the first support layer.

[0074] (Technical proposal 17) Further comprising a first connection section, A portion of the first connecting portion is connected to the first support portion, Another part of the first connection is connected to the movable part, The sensor according to technical proposal 16, wherein a third gap is provided between the base and the first connecting portion.

[0075] (Technical proposal 18) The second fixing part, The second support section and Furthermore, The substrate further includes a third region, The first region is located between the second region and the third region. The second fixing part is fixed to the third region, The second support portion is connected to the second fixing portion, The second support portion includes a second support layer, a third layer fixed to the second support layer, and a fourth layer, wherein at least a portion of the third layer is provided between the second support layer and the fourth layer, the third layer includes the first element and oxygen, and the fourth layer includes the second element and oxygen. The movable part is provided between the first support part and the second support part and is further supported by the second support part, as described in any one of Technical Proposals 1 to 17.

[0076] (Technical proposal 19) Further equipped with a second connection section, A portion of the second connecting portion is connected to the second support portion, Another part of the second connection is connected to the movable part, The sensor according to technical proposal 18, wherein a gap is provided between the base and the second connecting portion.

[0077] (Technical proposal 20) The thickness of the first layer is 1 nm or more and 1 μm or less. The thickness of the second layer is 0.1 nm or more and 1 μm or less. The sensor according to any one of Technical Proposals 1 to 19, wherein the thickness of the first support layer is 10 nm or more and 10 μm or less.

[0078] According to this embodiment, a sensor with high detection sensitivity can be provided.

[0079] Embodiments of the present invention have been described above with reference to examples. However, the present invention is not limited to these examples. For example, the specific configuration of each element included in the sensor, such as the substrate, fixed part, support part, layer, movable part, fixed electrode, and control unit, is included within the scope of the present invention as long as those skilled in the art can appropriately select from the known range to implement the present invention and obtain similar effects.

[0080] Combinations of two or more elements from each example, to the extent technically feasible, are also included within the scope of the present invention, insofar as they encompass the gist of the invention.

[0081] All sensors that a person skilled in the art can implement by appropriately modifying the design based on the sensors described above as embodiments of the present invention also fall within the scope of the present invention, insofar as they encompass the gist of the present invention.

[0082] Within the scope of the concept of this invention, a person skilled in the art would be able to conceive of various modifications and alterations, and it is understood that such modifications and alterations also fall within the scope of this invention.

[0083] While several embodiments of the present invention have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These novel embodiments can be carried out in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents. [Explanation of symbols]

[0084] 21, 22: First and second fixed parts, 30M: movable part, 31-34: first to fourth layers, 31L, 32L: first and second support layers, 31MO: oxide, 31c, 32c: first and second connection parts, 31h, 32h: first and second conductive members, 31s, 32s: first and second support parts, 35: movable electrode, 40: substrate, 41-43: first to third regions, 55: fixed electrode, 55a: insulating film, 70: control unit, 81H: target gas, 81O: oxygen, 110-112: sensors, CP1: concentration parameter, D1: first direction, G1-G5: first to fifth voids, ST1, ST2: first and second states, dz: distance, ΔC: change

Claims

1. A substrate including a first region and a second region, A fixed electrode fixed in the first region, The first fixing part fixed to the second region, A first support portion connected to the first fixed portion, the first support portion comprising a first support layer, a first layer, and a second layer, wherein in a first direction from the first support layer to the second layer, the first layer is provided between the first support layer and at least a part of the second layer, the first layer comprises a first element including at least one selected from the group consisting of Pt, Pd, and Ti, and oxygen, and the second layer comprises a second element different from the first element and oxygen, the first support portion, A movable part supported by the first support part, wherein a first gap is provided between the fixed electrode and the movable part, Equipped with, The sensor wherein the second element comprises at least one selected from the group consisting of Si and Al.

2. The sensor according to claim 1, wherein the second layer does not contain the first element, or the concentration of the first element in the second layer is lower than the concentration of the first element in the first layer.

3. The sensor according to claim 1, wherein, in a direction intersecting the first direction, the first layer is provided between a plurality of regions included in the second layer.

4. The sensor according to claim 1, wherein at least a portion of the first support layer is provided between a portion of the second layer and the first layer in a first direction.

5. The sensor according to claim 1, wherein the first layer is reduced by the target gas around the first support portion.

6. The sensor according to claim 5, wherein the gas to be detected includes hydrogen.

7. The concentration of the target gas in the first state is higher than the concentration of the target gas in the second state. The sensor according to any one of claims 1 to 4, wherein the first distance between the fixed electrode and the movable part in the first state is longer than the second distance between the fixed electrode and the movable part in the second state.

8. The concentration of the target gas in the first state is higher than the concentration of the target gas in the second state. The sensor according to any one of claims 1 to 4, wherein the first capacitance between the fixed electrode and the movable part in the first state is smaller than the second capacitance between the fixed electrode and the movable part in the second state.

9. The first support portion further includes a first conductive member, The sensor according to claim 1, wherein the temperature of the first support portion can be raised by the current flowing through the first conductive member.

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