Pressure sensor element

Abstract

Provided is a pressure sensor element that makes it possible to reduce influence of foreign matter on pressure detection accuracy. This pressure sensor element comprises a first substrate layer, a membrane layer, an electrode layer, and a second substrate layer that are sequentially laminated. The membrane layer has a diaphragm part and a periphery part surrounding the diaphragm part when viewed along the lamination direction. The first substrate layer faces the diaphragm part in the lamination direction via a communication space in communication with the outside through a hole part, and is bonded to the periphery part. The electrode layer has a base part facing the diaphragm part in the lamination direction via a sealed space, and a guard part surrounding the base part when viewed along the lamination direction, separated from the base part, and bonded to the periphery part. The second substrate layer is bonded to the electrode layer. The hole part penetrates the second substrate layer, the guard part, and the periphery part in the lamination direction, opens to the outside in the second substrate layer, and opens to the communication space in the periphery part.

Description

pressure sensor element

[0001] The present invention relates to a pressure sensor element for detecting external pressure.

[0002] An example of a pressure sensor element for detecting external pressure is disclosed in Japanese Patent Application Laid-Open No. 2003-222299.

[0003] The pressure sensor element disclosed in Patent Document 1 has a base portion and a diaphragm portion facing each other across a pressure reference chamber. When pressure acts on the diaphragm portion from the outside, the diaphragm portion bends, changing the distance between the base portion and the diaphragm portion. This causes a change in the capacitance between the base portion and the diaphragm portion. The pressure acting on the diaphragm portion is detected based on the change in capacitance.

[0004] International Publication No. 2023 / 032501

[0005] In the pressure sensor element disclosed in Patent Document 1, the diaphragm portion is exposed to the outside of the pressure sensor element through an exposure hole. Therefore, there is a risk that foreign matter such as water may adhere to the diaphragm portion. If foreign matter adheres to the diaphragm portion, there is a risk that the pressure detection accuracy may be reduced.

[0006] SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned problems and to provide a pressure sensor element that can reduce the influence of foreign matter on the accuracy of pressure detection.

[0007] a second substrate layer laminated on the electrode layer opposite the membrane layer, wherein the membrane layer has a conductive diaphragm portion and a peripheral portion surrounding the diaphragm portion when viewed along a stacking direction; the first substrate layer faces the diaphragm portion of the membrane layer in the stacking direction via a communication space that communicates with the outside through at least one hole, and is joined to the peripheral portion of the membrane layer; the electrode layer has a conductive base portion facing the diaphragm portion in the stacking direction via a sealed space, and a guard portion that surrounds the base portion when viewed along the stacking direction, is spaced apart from the base portion, and is joined to the peripheral portion of the membrane layer; and the second substrate layer is joined to the electrode layer, The hole penetrates the second substrate layer, the guard portion of the electrode layer, and the peripheral portion of the membrane layer in the stacking direction, opens to the outside in the second substrate layer, and opens to the communicating space at the peripheral portion of the membrane layer.

[0008] According to the present disclosure, the influence of foreign matter on the accuracy of pressure detection can be reduced.

[0009] 1 is a schematic cross-sectional view of a pressure sensor according to an embodiment of the present disclosure; FIG. 2 is a schematic plan view of a pressure sensor element according to a first embodiment of the present disclosure; FIG. 3 is a schematic cross-sectional view showing the A-A cross section of FIG. 2; FIG. 4 is a schematic cross-sectional view showing the B-B cross section of FIG. 2; FIG. 5 is a schematic cross-sectional view illustrating a process subsequent to FIG. 5 in the method of manufacturing a pressure sensor element according to the first embodiment of the present disclosure; FIG. 6 is a schematic cross-sectional view illustrating a process subsequent to FIG. 7 in the method of manufacturing a pressure sensor element according to the first embodiment of the present disclosure; FIG. 8 is a schematic cross-sectional view illustrating a process subsequent to FIG. 9 in the method of manufacturing a pressure sensor element according to the first embodiment of the present disclosure; FIG. 2 is a schematic cross-sectional view illustrating a process subsequent to FIG. 10 in the method of manufacturing a pressure sensor element according to the first embodiment of the present disclosure, showing the CC cross section of FIG. 2; FIG. 3 is a schematic plan view of a modified example of the pressure sensor element according to the first embodiment of the present disclosure; FIG. 4 is a schematic cross-sectional view corresponding to the A-A cross section of FIG. 2 in the modified example of the pressure sensor element according to the first embodiment of the present disclosure. 16 is a schematic cross-sectional view corresponding to the A-A cross section of Fig. 2 in a modified example of the pressure sensor element according to the first embodiment of the present disclosure. 2 is a schematic cross-sectional view corresponding to the A-A cross section of Fig. 2 in a modified example of the pressure sensor element according to the first embodiment of the present disclosure. 2 is a schematic plan view of the pressure sensor element according to a second embodiment of the present disclosure. 17 is a schematic cross-sectional view showing the D-D cross section of Fig. 16. 18 is a schematic plan view of the pressure sensor element according to the second embodiment of the present disclosure.

[0010] An example of the present disclosure will now be described with reference to the accompanying drawings. Note that the following description is merely illustrative in nature and is not intended to limit the present disclosure, its applications, or its uses. The drawings are schematic, and the ratios of dimensions and the like do not necessarily correspond to reality. Furthermore, in the following description, terms indicating specific directions or positions (e.g., terms including "upper," "lower," "right," "left," "front," and "rear") are used as necessary. However, the use of terms indicating specific directions or positions is intended to facilitate understanding of the present disclosure with reference to the drawings, and the meanings of these terms do not limit the technical scope of the present disclosure.

[0011] 1 is a longitudinal cross-sectional view of a pressure sensor according to a first embodiment of the present invention. The pressure sensor 1 is capable of detecting pressure and is mounted on, for example, a mobile object such as an automobile, or a consumer device such as a smartphone or a smartwatch.

[0012] 1, the pressure sensor 1 includes a substrate 2, a pressure sensor element 10, an application specific integrated circuit (ASIC) 3, and a resin package 4. Hereinafter, the application specific integrated circuit 3 will be referred to as the ASIC 3.

[0013] The substrate 2 is a plate-shaped member. The substrate 2 is a rigid substrate such as a glass epoxy substrate or a ceramic substrate, but is not limited to these. For example, the substrate 2 may be a lead frame.

[0014] The substrate 2 has a rectangular parallelepiped shape that is thin in a stacking direction 100. The stacking direction 100 is a direction perpendicular to the upper surface 2A of the substrate 2. The stacking direction 100 is also the direction in which the layers included in the pressure sensor element 10, which will be described later, are stacked. The layers included in the pressure sensor element 10 are a first substrate layer 20, a membrane layer 30, an electrode layer 40, and a second substrate layer 50 (see FIG. 3 ).

[0015] The substrate 2 is rectangular when viewed along the stacking direction 100. The shape of the substrate 2 is not limited to a rectangular parallelepiped shape (a shape that is rectangular when viewed along the stacking direction 100). For example, the substrate 2 may be a polygon other than a rectangle when viewed along the stacking direction 100.

[0016] The pressure sensor element 10 is for detecting pressure. The pressure sensor element 10 is a capacitance type element. In the present disclosure, the pressure sensor element 10 is a MEMS (Micro Electro Mechanical Systems) element.

[0017] The pressure sensor element 10 is adhered to the upper surface 2A of the substrate 2 by a die attach film, a die attach material, or the like. In this way, the pressure sensor element 10 is mounted on the upper surface 2A of the substrate 2. Note that the means for mounting the pressure sensor element 10 on the substrate 2 is not limited to the above-mentioned adhesion, and various known means can be used.

[0018] The pressure sensor element 10 has a rectangular parallelepiped shape. The shape of the pressure sensor element 10 is not limited to a rectangular parallelepiped shape (a quadrilateral shape when viewed along the stacking direction 100). For example, the pressure sensor element 10 may have a polygonal shape other than a quadrilateral when viewed along the stacking direction 100, or may have a cylindrical shape.

[0019] The configuration of the pressure sensor element 10 will be described in detail later.

[0020] The ASIC 3 is mounted on the upper surface 2A of the substrate 2. The ASIC 3 includes a package that covers the integrated circuit. In the first embodiment, the package is made of silicon, but it may be made of a material other than silicon.

[0021] The ASIC 3 is adhered to the upper surface 2A of the substrate 2 by a die attach film, a die attach material, or the like. In this way, the ASIC 3 is mounted on the upper surface 2A of the substrate 2. Note that the means for mounting the ASIC 3 on the substrate 2 is not limited to the above-mentioned adhesion, and various known means can be used.

[0022] The ASIC 3 has a rectangular parallelepiped shape. However, the shape of the ASIC 3 is not limited to a rectangular parallelepiped shape (a quadrilateral shape when viewed along the stacking direction 100). For example, the ASIC 3 may have a polygonal shape other than a quadrilateral when viewed along the stacking direction 100.

[0023] The pressure sensor element 10 and the ASIC 3 are electrically connected via bonding wires 5 and the substrate 2, as described in detail below. A pad 80 is formed on the pressure sensor element 10. A pad 2B is formed on the upper surface 2A of the substrate 2. The pad 80 and the pad 2B are electrically connected by bonding wires 5. A wiring pattern (not shown) is formed on the upper surface 2A of the substrate 2. The wiring pattern extends from the pad 2B. The ASIC 3 is electrically connected to the pad 2B via the wiring pattern.

[0024] 1, for convenience of explanation, one pad 80, one pad 2B, and one bonding wire 5 are depicted, but the number of each is not limited to one. For example, in the first embodiment, the pressure sensor element 10 has three pads 80 (see FIG. 2), and the pad 2B and the bonding wire 5 are provided corresponding to each of the three pads 80.

[0025] The configuration for electrically connecting the pressure sensor element 10 and the ASIC 3 is not limited to the above-described configuration. For example, the pressure sensor element 10 and the ASIC 3 may be electrically connected by bonding wires without going through the substrate 2.

[0026] The ASIC 3 includes a signal processing circuit that processes the signal output from the pressure sensor element 10 and outputs the processed signal to the substrate 2. For example, the ASIC 3 includes a converter, a filter, a temperature sensor, a processor, a memory, etc. The converter converts the voltage signal output from the pressure sensor element 10 into a digital signal. The filter filters the digital signal from the converter. The temperature sensor detects temperature. The processor corrects the filtered digital signal based on the temperature detected by each temperature sensor. The memory stores correction coefficients and the like used when correcting the digital signal using the detected temperature.

[0027] The resin package 4 is made of a resin such as epoxy resin, and is provided on the upper surface 2A of the substrate 2. The resin package 4 covers the upper surface 2A of the substrate 2, the pressure sensor element 10, the ASIC 3, and the bonding wires 5.

[0028] The resin package 4 has an exposure hole 4A. A portion of the pressure sensor element 10 is exposed to the outside of the pressure sensor 1 through the exposure hole 4A. In the first embodiment, the portion of the pressure sensor element 10 is a portion of the upper surface 50A of the second substrate layer 50 of the pressure sensor element 10 that includes a hole portion 63 that opens to the upper surface 50A (see FIGS. 2 and 3 ).

[0029] In the first embodiment, the pressure sensor element 10 and the ASIC 3 are arranged side by side on the upper surface 2A of the substrate 2 as shown in Fig. 1, but this is not limiting. For example, the pressure sensor element 10 may be supported on the upper surface of the ASIC 3.

[0030] The configuration of the pressure sensor element 10 will be described below.

[0031] Fig. 2 is a schematic plan view of the pressure sensor element according to the first embodiment of the present disclosure, Fig. 3 is a schematic cross-sectional view showing the AA cross section of Fig. 2, and Fig. 4 is a schematic cross-sectional view showing the BB cross section of Fig. 2.

[0032] As shown in FIGS. 2, 3, and 4, the pressure sensor element 10 includes a first substrate layer 20, a membrane layer 30, an electrode layer 40, and a second substrate layer 50.

[0033] 3 and 4 , the membrane layer 30 is laminated on the first substrate layer 20. The electrode layer 40 is laminated on the membrane layer 30 on the side opposite the first substrate layer 20. The second substrate layer 50 is laminated on the electrode layer 40 on the side opposite the membrane layer 30.

[0034] The first substrate layer 20 includes a guard layer 21, a first insulating layer 22, and a first conductive layer 23. The first insulating layer 22 is laminated on the guard layer 21. The first conductive layer 23 is laminated on the side of the first insulating layer 22 opposite the guard layer 21. When viewed along the stacking direction 100, the first insulating layer 22 and the first conductive layer 23 are provided on the peripheral portion of the first substrate layer 20. As a result, when viewed along the stacking direction 100, the area inside the peripheral portion is recessed in the stacking direction 100. This recessed portion is a communicating space 61. The communicating space 61 is defined by the upper surface 21A of the guard layer 21, the inner surfaces 20A of the first insulating layer 22 and the first conductive layer 23, and the lower surface 30A of the membrane layer 30.

[0035] In the first embodiment, the thickness of the first substrate layer 20, in other words, the length of the first substrate layer 20 in the stacking direction 100, is 100 to 300 μm.

[0036] In the first embodiment, the guard layer 21 is made of conductive silicon (Si), and the first insulating layer 22 is made of electrically insulating silicon dioxide (SiO ２ ), and the first conductive layer 23 is made of conductive polysilicon (Poly-Si).

[0037] The membrane layer 30 includes a diaphragm portion 31 and a peripheral portion 32 .

[0038] The diaphragm portion 31 has both surfaces in the stacking direction 100 that are not in contact with other layers of the pressure sensor element 10. In other words, the diaphragm portion 31 has both surfaces in the stacking direction 100 that face space. More specifically, one surface of the diaphragm portion 31 in the stacking direction 100 faces the communicating space 61. In other words, the diaphragm portion 31 and the guard layer 21 of the first substrate layer 20 face each other in the stacking direction 100 via the communicating space 61. Furthermore, the other surface of the diaphragm portion 31 in the stacking direction 100 faces the sealed space 62, which will be described later. As described above, the diaphragm portion 31 can bend in the stacking direction 100.

[0039] When viewed along the stacking direction 100, the peripheral edge portion 32 surrounds the diaphragm portion 31. The peripheral edge portion 32 is configured integrally with the diaphragm portion 31.

[0040] At least a portion of the surfaces of the peripheral portion 32 on both sides of the membrane layer 30 in the stacking direction 100 is in contact with other layers of the pressure sensor element 10. In this embodiment, a portion of one surface of the peripheral portion 32 in the stacking direction 100 is bonded to the first conductive layer 23 of the first substrate layer 20. The remaining portion of the surface of the peripheral portion 32 on one side in the stacking direction 100 faces the communicating space 61. The other surface of the peripheral portion 32 in the stacking direction 100 is bonded to the second insulating layer 41 of the electrode layer 40.

[0041] In the first embodiment, the thickness of the membrane layer 30 is 3 to 5 μm. In the first embodiment, the membrane layer 30 is made of conductive silicon (Si).

[0042] The electrode layer 40 includes a second insulating layer 41 , a second conductive layer 42 , and a third insulating layer 43 .

[0043] The second insulating layer 41 is laminated on the peripheral edge portion 32 of the membrane layer 30. The second conductive layer 42 is laminated on the second insulating layer 41 on the side opposite the membrane layer 30. The third insulating layer 43 is laminated on the second conductive layer 42 on the side opposite the second insulating layer 41.

[0044] The second insulating layer 41 is bonded to the peripheral edge portion 32 of the membrane layer 30. The second insulating layer 41 has a through hole that penetrates the second insulating layer 41 in the stacking direction 100. The through hole forms a sealed space 62. One side of the sealed space 62 in the stacking direction 100 is closed by the diaphragm portion 31 of the membrane layer 30. The other side of the sealed space 62 in the stacking direction 100 is closed by the second conductive layer 42. The sides of the sealed space 62 are closed by the second insulating layer 41.

[0045] The second conductive layer 42 includes a base portion 421 and a guard portion 422 .

[0046] The base portion 421 faces the diaphragm portion 31 of the membrane layer 30 in the stacking direction 100 with the sealed space 62 interposed therebetween.

[0047] When viewed along the stacking direction 100, the guard portion 422 surrounds the base portion 421. The guard portion 422 is separated from the base portion 421 via a gap 42A. The gap 42A is in communication with the sealed space 62. As a result, the gap 42A is part of the sealed space 62. The guard portion 422 is joined to the second insulating layer 41. Note that the second insulating layer 41 also surrounds the base portion 421 when viewed along the stacking direction 100, and is separated from the base portion 421. The guard portion 422 and the second insulating layer 41 are an example of a joining portion.

[0048] The third insulating layer 43 is bonded to the base portion 421 and the guard portion 422 of the second conductive layer 42 .

[0049] In the first embodiment, the thickness of the electrode layer 40 is 1 to 5 μm. In the first embodiment, the second conductive layer 42 is made of conductive polysilicon (Poly-Si). In the first embodiment, the second insulating layer 41 and the third insulating layer 43 are made of electrically insulating silicon dioxide (SiO ２ ) is composed of

[0050] The second substrate layer 50 is bonded to the third insulating layer 43 of the electrode layer 40. In the first embodiment, the thickness of the second substrate layer 50 is 100 to 150 μm. In the first embodiment, the second substrate layer 50 is made of conductive silicon (Si).

[0051] The materials constituting the layers of the pressure sensor element 10 described above are not limited to the materials mentioned above.

[0052] 2, 3, and 4, the pressure sensor element 10 has one hole 63. The communication space 61 communicates with the outside of the pressure sensor element 10 through the one hole 63. Note that the pressure sensor element 10 may have a plurality of holes 63, and the communication space 61 may communicate with the outside of the pressure sensor element 10 through the plurality of holes 63.

[0053] The hole 63 penetrates the second substrate layer 50, the third insulating layer 43 of the electrode layer 40, the joint portion of the electrode layer 40 (the guard portion 422 and the second insulating layer 41), and the peripheral edge portion 32 of the membrane layer 30 in the stacking direction 100. The hole 63 opens to the outside of the pressure sensor element 10 at the upper surface 50A of the second substrate layer 50. As a result, the hole 63 is exposed to the outside of the pressure sensor element 10. The hole 63 opens to the communication space 61 at the lower surface 30A of the peripheral edge portion 32. As a result, the communication space 61 communicates with the outside of the pressure sensor element 10 through the hole 63. As described above, the hole 63 opened at the upper surface 50A of the second substrate layer 50 is exposed to the outside of the pressure sensor 1 through the exposure hole 4A. As a result, the communication space 61 is exposed to the outside of the pressure sensor 1 through the hole 63 and the exposure hole 4A.

[0054] 2, the hole 63 has a rectangular shape when viewed along the stacking direction 100. The shape of the hole 63 is arbitrary. For example, when viewed along the stacking direction 100, the hole 63 may have a circular, elliptical, triangular, or other shape, or may be an elongated hole.

[0055] As shown in FIG. 3 , in the first embodiment, the hole 63 includes a large-diameter portion 631 and a small-diameter portion 632. When viewed along the stacking direction 100, the area of ​​the large-diameter portion 631 is larger than the area of ​​the small-diameter portion 632. When viewed along the stacking direction 100, the length of the longest portion of the large-diameter portion 631 is longer than the length of the longest portion of the small-diameter portion 632. In the first embodiment, the length of the longest portion of the large-diameter portion 631 is the longitudinal length of a rectangle when viewed along the stacking direction 100. The length of the longest portion of the small-diameter portion 632 is the same as that of the large-diameter portion 631 and is the longitudinal length of a rectangle when viewed along the stacking direction 100. In the first embodiment, the hole 63 has two portions (the large-diameter portion 631 and the small-diameter portion 632) of different sizes, in other words, one step, but this configuration is not limited thereto. For example, the hole 63 may be the same size regardless of its position in the stacking direction 100. In other words, the hole 63 may extend straight without any steps along the stacking direction 100. Furthermore, for example, the hole 63 may have two or more steps.

[0056] The diaphragm portion 31 of the membrane layer 30 and the base portion 421 of the electrode layer 40 face each other across the sealed space 62, which can generate capacitance. The generated capacitance varies depending on the distance between the diaphragm portion 31 and the base portion 421.

[0057] Pressure acts on the diaphragm portion 31 from the outside of the pressure sensor 1 through the exposure hole 4A and the hole portion 63. The greater this pressure, the greater the amount of deflection of the diaphragm portion 31 toward the sealed space 62. This reduces the gap between the diaphragm portion 31 and the base portion 421. As a result, the electrostatic capacitance generated between the diaphragm portion 31 and the base portion 421 increases.

[0058] The diaphragm portion 31 and the base portion 421 are each electrically connected to a different pad 80 (see FIG. 2). Note that in FIG. 2, the three pads 80 are supported on the upper surface 50A of the second substrate layer 50 and are shown as being electrically connected to one another via the upper surface 50A, but in reality, the three pads 80 are electrically insulated from one another. In other words, the pads 80 electrically connected to the diaphragm portion 31 and the pads 80 electrically connected to the base portion 421 are electrically insulated from one another.

[0059] The ASIC 3 (see FIG. 1) calculates the capacitance generated in the diaphragm portion 31 and the base portion 421 based on the voltage or current between the pad 80 connected to the diaphragm portion 31 and the pad 80 connected to the base portion 421. The ASIC 3 calculates the pressure acting on the diaphragm portion 31 based on the calculated capacitance.

[0060] 2, 3, and 4, the pressure sensor element 10 has two first trench portions 71 and one second trench portion 72. The number of first trench portions 71 included in the pressure sensor element 10 is not limited to two. The number of second trench portions 72 included in the pressure sensor element 10 is not limited to one.

[0061] Each of the two first trench portions 71 has a rectangular ring shape when viewed along the stacking direction 100. In other words, each of the two first trench portions 71 is an endless ring shape. The second trench portion 72 has a rectangular ring shape with a missing portion when viewed along the stacking direction 100. In other words, the second trench portion 72 is an ended ring shape. In the first embodiment, each of the first trench portion 71 and the second trench portion 72 has a square ring shape when viewed along the stacking direction 100.

[0062] The shapes of the first trench portion 71 and the second trench portion 72 are not limited to the shapes described above. For example, the first trench portion 71 and the second trench portion 72 may be annular. For example, the first trench portion 71 may be annular with ends, and the second trench portion 72 may be annular without ends. For example, the first trench portion 71 and the second trench portion 72 may have a ring shape as a whole when viewed along the stacking direction 100 by providing a plurality of linear grooves arranged at intervals. For example, the first trench portion 71 and the second trench portion 72 are not limited to being annular, and may have a linear shape that extends straight or curves. The two first trench portions 71 may have different shapes or the same shape. The first trench portion 71 and the second trench portion 72 may have different shapes. For example, when viewed along the stacking direction 100, the first trench portion 71 may be annular and the second trench portion 72 may be linear. The first trench portion 71 and the second trench portion 72 may have the same shape.

[0063] In addition, in FIG. 2, the two first trench portions 71 and one second trench portion 72 are depicted as having the same width, but the first trench portion 71 and the second trench portion 72 may have different widths.

[0064] 3 and 4 , the first trench portion 71 opens to the upper surface 50A of the second substrate layer 50. That is, the first trench portion 71 opens to the outside of the pressure sensor element 10 in the second substrate layer 50. The depth direction of the first trench portion 71 is the stacking direction 100. In the first embodiment, the first trench portion 71 penetrates the second substrate layer 50 in the stacking direction 100. As a result, the third insulating layer 43 of the electrode layer 40 forms the bottom portion 71A of the first trench portion 71.

[0065] In the first embodiment, the depth of the first trench portion 71 is the same as the length of the second substrate layer 50 in the stacking direction 100. However, the depth of the first trench portion 71 is not limited to the length of the second substrate layer 50 in the stacking direction 100. The first trench portion 71 only needs to be provided in at least the second substrate layer 50 out of the second substrate layer 50, the third insulating layer 43, the guard portion 422, and the second insulating layer 41 of the electrode layer 40, and the peripheral portion 32 of the membrane layer 30.

[0066] For example, the first trench portion 71 does not have to penetrate the second substrate layer 50 in the stacking direction 100. In this case, the second substrate layer 50 forms the bottom 71A of the first trench portion 71. Alternatively, for example, the first trench portion 71 may penetrate the second substrate layer 50 and the third insulating layer 43 and guard portion 422 of the electrode layer 40. In this case, the second insulating layer 41 of the electrode layer 40 forms the bottom 71A of the first trench portion 71. Alternatively, for example, the first trench portion 71 may penetrate the second substrate layer 50 and the third insulating layer 43, guard portion 422, and second insulating layer 41 of the electrode layer 40, and may be provided up to the middle of the peripheral portion 32 of the membrane layer 30. In this case, the peripheral portion 32 forms the bottom 71A of the first trench portion 71.

[0067] The second trench portion 72 opens to the lower surface 30A of the peripheral portion 32 of the membrane layer 30. That is, the second trench portion 72 opens to the communicating space 61 at the peripheral portion 32. The depth direction of the second trench portion 72 is the stacking direction 100. In the first embodiment, the second trench portion 72 penetrates the peripheral portion 32 and the second insulating layer 41, guard portion 422, and third insulating layer 43 of the electrode layer 40, and is provided partway through the second substrate layer 50. As a result, the second substrate layer 50 forms the bottom portion 72A of the second trench portion 72.

[0068] The depth of the second trench portion 72 is not limited to the depth shown in Fig. 3. In the first embodiment, the second trench portion 72 may be provided in at least the peripheral portion 32 among the peripheral portion 32, the second insulating layer 41, the guard portion 422, and the third insulating layer 43 of the electrode layer 40, and the second substrate layer 50.

[0069] For example, the second trench portion 72 may penetrate the peripheral portion 32 and the second insulating layer 41 and guard portion 422 of the electrode layer 40. In this case, the third insulating layer 43 of the electrode layer 40 forms the bottom portion 72A of the second trench portion 72.

[0070] In the first embodiment, as shown in FIGS. 2 and 3 , the first trench portion 71 and the second trench portion 72 are located outside the base portion 421 and the diaphragm portion 31 when viewed along the stacking direction 100 .

[0071] 2, in the first embodiment, when viewed along the stacking direction 100, the second trench portion 72 is sandwiched between two first trench portions 71. As a result, when viewed along a direction perpendicular to the stacking direction 100, the two first trench portions 71 and the second trench portion 72 are aligned, as shown in FIG.

[0072] As shown in FIG. 3 , in the stacking direction 100 , the bottom 71 A of the first trench portion 71 is located closer to the first substrate layer 20 than the bottom 72 A of the second trench portion 72 .

[0073] Because the first trench portion 71 and the second trench portion 72 are configured as described above, the membrane layer 30, the electrode layer 40, and the second substrate layer 50 have a meandering shape from the outside to the inside of the pressure sensor element 10 when viewed along a direction perpendicular to the stacking direction 100, as shown by the dotted arrows in Figures 3 and 4.

[0074] In the first embodiment, as shown in FIG. 2 , when viewed along the stacking direction 100, the area of ​​the hole 63 is smaller than the area of ​​the first trench 71 and smaller than the area of ​​the second trench 72. Note that, when viewed along the stacking direction 100, the area of ​​the hole 63 may be larger than the area of ​​the first trench 71 and smaller than the area of ​​the second trench 72, or may be smaller than the area of ​​the first trench 71 and larger than the area of ​​the second trench 72. The area of ​​the hole 63 when viewed along the stacking direction 100 is, for example, the cross-sectional area of ​​the portion of the hole 63 where the cross-sectional area is smallest. In the first embodiment, the portion of the hole 63 where the cross-sectional area is smallest is the small diameter portion 632 shown in FIG. 3 . That is, the cross-sectional area of ​​the portion of the hole 63 where the cross-sectional area is smallest is the cross-sectional area of ​​the small diameter portion 632. The cross-sectional area of ​​the small diameter portion 632 shown in FIG. 3 is the area of ​​the small diameter portion 632 when viewed along the stacking direction 100.

[0075] 2 , in the first embodiment, the length L1 of the longest part of the hole 63 when viewed along the stacking direction 100 is shorter than the short side S1 of the trench portion that forms a rectangular ring in the first trench portion 71. In addition, the length L1 of the longest part of the hole 63 when viewed along the stacking direction 100 is shorter than the short side S2 of the trench portion that forms a rectangular ring in the second trench portion 72. Note that in the first embodiment, since each of the first trench portion 71 and the second trench portion 72 forms a square ring when viewed along the stacking direction 100, the short side and the long side have the same length.

[0076] 3 , in the first embodiment, the length L2 of the longest portion of the hole 63 at the minimum cross-sectional area thereof as viewed along the stacking direction 100 is shorter than the width W1 of the first trench 71 as viewed along the stacking direction 100. The length L2 is also shorter than the width W2 of the second trench 72 as viewed along the stacking direction 100. In the first embodiment, the minimum cross-sectional area of ​​the hole 63 is the small diameter portion 632. Note that the length L2 may be longer than the width W1 and shorter than the width W2, or may be shorter than the width W1 and longer than the width W2.

[0077] <Method of Manufacturing Pressure Sensor Element> An example of a method of manufacturing the pressure sensor element 10 according to the first embodiment of the present disclosure will be described below with reference to FIGS. 5 to 11 . FIG. 5 is a schematic cross-sectional view illustrating a process subsequent to that shown in FIG. 5 in the method of manufacturing the pressure sensor element according to the first embodiment of the present disclosure. FIG. 7 is a schematic cross-sectional view illustrating a process subsequent to that shown in FIG. 6 in the method of manufacturing the pressure sensor element according to the first embodiment of the present disclosure. FIG. 8 is a schematic cross-sectional view illustrating a process subsequent to that shown in FIG. 7 in the method of manufacturing the pressure sensor element according to the first embodiment of the present disclosure. FIG. 9 is a schematic cross-sectional view illustrating a process subsequent to that shown in FIG. 8 in the method of manufacturing the pressure sensor element according to the first embodiment of the present disclosure. FIG. 10 is a schematic cross-sectional view illustrating a process subsequent to that shown in FIG. 9 in the method of manufacturing the pressure sensor element according to the first embodiment of the present disclosure. FIG. 11 is a schematic cross-sectional view illustrating a process subsequent to that shown in FIG. 10 in the method of manufacturing the pressure sensor element according to the first embodiment of the present disclosure, showing the CC cross section of FIG. 2 .

[0078] The pressure sensor element 10 is manufactured by dividing a laminate into a plurality of pieces. The laminate is an integrated structure in which a plurality of pressure sensor elements 10 are arranged. For the sake of convenience, only a portion of the laminate corresponding to one pressure sensor element 10 is shown in FIGS. 5 to 11. In the manufacturing method described below, the pressure sensor element 10 is manufactured by bonding three silicon substrates (guard layer 21, membrane layer 30, and second substrate layer 50) to each other via insulating layers and conductive layers.

[0079] (First Film Formation Process) First, the first film formation process is performed. In the first film formation process, as shown in FIG. 5 , a third insulating layer 43 is formed and patterned on a second substrate layer 50, which is a silicon substrate, and a second conductive layer 42 is formed and patterned on the third insulating layer 43. In this process and other processes described below, film formation and patterning are performed by known means such as photolithography. A gap 43A is formed by patterning the third insulating layer 43. A gap 42A is formed by patterning the second conductive layer 42. This divides the second conductive layer 42 into a base portion 421 and a guard portion 422. When the second conductive layer 42 is formed, the second conductive layer 42 enters the gap 43A. This establishes electrical continuity between the second substrate layer 50 and the second conductive layer 42.

[0080] (Second Film Forming Process) Next, the second film forming process is performed. In the second film forming process, as shown in FIG. 6 , a second insulating layer 41 is formed and patterned on the membrane layer 30, which is a silicon substrate. By patterning, a non-film formed portion 41A is formed. The non-film formed portion 41A becomes a sealed space 62 in the first bonding process described below. Of the membrane layer 30, the portion that does not contact the second insulating layer 41 and faces the non-film formed portion 41A is the diaphragm portion 31, and the portion that contacts the second insulating layer 41 is the peripheral portion 32. Note that, to ensure thickness, the membrane layer 30 is laminated on the handle layer 6. The second film forming process may be performed before the first film forming process or may be performed in parallel with the first film forming process.

[0081] (First Bonding Step) Next, the first bonding step is performed. In the first bonding step, as shown in FIG. 7 , the second substrate layer 50 and the membrane layer 30 are bonded via the second insulating layer 41, the second conductive layer 42, and the third insulating layer 43. Specifically, the second conductive layer 42 formed on the second substrate layer 50 and the second insulating layer 41 formed on the membrane layer 30 are bonded together. As a result, the non-film-formed portion 41A (see FIG. 6 ) is covered by the second conductive layer 42, forming an enclosed space 62. Note that in the first bonding step, the handle layer 6 (see FIG. 6 ) is removed. Note that the bonding performed in the first bonding step and the second bonding step described below is performed by a known method, such as fusion bonding.

[0082] (First Etching Step) Next, the first etching step is performed. In the first etching step, as shown in FIG. 8 , etching is performed from the peripheral edge portion 32 of the membrane layer 30 along the stacking direction 100. In the first etching step and the second etching step described below, etching is performed by a known method such as the BOSCH method. As a result, the hole portion 63 and the second trench portion 72 are formed. The formed hole portion 63 and the second trench portion 72 penetrate the peripheral edge portion 32, the second insulating layer 41, the second conductive layer 42, and the third insulating layer 43 in the stacking direction 100 and extend into the interior of the second substrate layer 50.

[0083] (Third Film Forming Process) Next, the third film forming process is performed. In the third film forming process, as shown in FIG. 9 , a first insulating layer 22 is formed and patterned on the guard layer 21, and a first conductive layer 23 is formed and patterned on the first insulating layer 22. Gaps 22A are formed by patterning the first insulating layer 22. When the first conductive layer 23 is formed, the first conductive layer 23 enters the gaps 22A. This establishes electrical continuity between the first conductive layer 23 and the guard layer 21. Non-film-formed portions 20B are formed by patterning the first insulating layer 22 and the first conductive layer 23. The non-film-formed portions 20B become the communicating spaces 61 in the second bonding process described below.

[0084] (Second Bonding Step) Next, the second bonding step is performed. In the second bonding step, as shown in FIG. 10 , the membrane layer 30 and the guard layer 21 are bonded via the first insulating layer 22 and the first conductive layer 23. Specifically, the membrane layer 30 is bonded to the side of the first conductive layer 23 opposite the first insulating layer 22. As a result, the non-film-formed portion 20B (see FIG. 9 ) is covered by the membrane layer 30, and a communication space 61 is formed. At this time, the entire diaphragm portion 31 and a part of the peripheral portion 32 of the membrane layer 30 are not in contact with the first conductive layer 23. Furthermore, the hole portion 63 and the second trench portion 72 are communicated with the communication space 61. Note that in the second bonding step, the side of the second substrate layer 50 opposite the third insulating layer 43 is ground to adjust the thickness of the second substrate layer 50.

[0085] (Second Etching Step) Next, the second etching step is performed. In the second etching step, etching is performed from the upper surface 50A of the second substrate layer 50 along the stacking direction 100, as shown in FIG.

[0086] Part of the etching is performed at a position that overlaps with the hole 63 formed in the first etching step when viewed along the stacking direction 100. As a result, the hole 63 penetrates the second substrate layer 50, the third insulating layer 43, the second conductive layer 42, the second insulating layer 41, and the peripheral edge portion 32 in the stacking direction 100. As a result, the communication space 61 communicates with the outside of the pressure sensor element 10 through the hole 63. Note that the hole 63 formed in the second substrate layer 50 by etching the second substrate layer 50 in the second etching step is the large diameter portion 631. On the other hand, the hole 63 formed in a layer other than the second substrate layer 50 by etching in the first etching step is the small diameter portion 632.

[0087] The remainder of the etching is performed adjacent to and sandwiching the second trench portion 72 formed in the first etching step, thereby forming two first trench portions 71 in the second substrate layer 50.

[0088] (Pad Forming Step) Next, the pad forming step is performed. In the pad forming step, the pad 80 is formed and patterned on the upper surface 50A of the second substrate layer 50, as shown in FIG.

[0089] Next, a singulation step is performed in which the laminate in which the plurality of pressure sensor elements 10 are arranged is cut into individual pressure sensor elements 10 .

[0090] The following describes the configuration of a modified example of the first embodiment. In the following description, the same reference numerals are used to designate components that have been previously described, and their descriptions are generally omitted, and are described only when necessary.

[0091] <Modification> FIG. 12 is a schematic plan view of a modification of the pressure sensor element according to the first embodiment of the present disclosure.

[0092] In the first embodiment, as shown in Fig. 2 , the hole 63 is provided outside the first trench 71 when viewed along the stacking direction 100. However, the position of the hole 63 is not limited to the position shown in Fig. 2 . For example, as shown in Fig. 12 , the hole 63 may be provided in a missing portion of the first trench 71 and the second trench 72 when viewed along the stacking direction 100.

[0093] 13 to 15 are schematic cross-sectional views corresponding to the cross section AA in FIG. 2 in modified examples of the pressure sensor element according to the first embodiment of the present disclosure.

[0094] 3, a sealed space 62 is formed by forming a step between the membrane layer 30 and the second insulating layer 41 laminated on the membrane layer 30. However, the configuration of the sealed space 62 is not limited to the configuration shown in FIG.

[0095] For example, as shown in FIGS. 13 to 15, the pressure sensor elements 10B, 10C, and 10D may not include the second insulating layer 41.

[0096] In the pressure sensor element 10B shown in FIG. 13, a step is formed between the diaphragm portion 31 and the peripheral edge portion 32 of the membrane layer 30, thereby forming a sealed space 62.

[0097] In the pressure sensor element 10C shown in FIG. 14, a step is formed between the base portion 421 and the guard portion 422 of the second conductive layer 42, thereby forming a sealed space 62.

[0098] 15 , the third insulating layer 43 includes a central portion 431 and a surrounding portion 432 that surrounds the central portion 431 when viewed along the stacking direction 100. A step is formed between the central portion 431 and the surrounding portion 432, thereby forming a step between the base portion 421 and the guard portion 422. This step between the base portion 421 and the guard portion 422 forms an enclosed space 62.

[0099] The configuration of the communication space 61, like the sealed space 62, is not limited to the configuration shown in FIG.

[0100] According to the first embodiment, air can flow from the outside of the pressure sensor element 10 to the communication space 61 through the hole 63. When the pressure of the air flowing into the communication space 61 acts on the diaphragm portion 31, the diaphragm portion 31 bends toward the base portion 421, changing the distance between the base portion 421 and the diaphragm portion 31. This causes the capacitance between the base portion 421 and the diaphragm portion 31 to vary. Based on this variation in capacitance, the pressure acting on the diaphragm portion 31 can be detected.

[0101] According to the first embodiment, the base portion 421 is covered by the guard portion 422, the membrane layer 30, and the second substrate layer 50, and is therefore not exposed to the outside of the pressure sensor element 10. Furthermore, the diaphragm portion 31 is covered by the peripheral portion 32, the electrode layer 40, and the first substrate layer 20, and is therefore not exposed to the outside of the pressure sensor element 10 except for exposure through the hole portion 63. This makes it possible to suppress adhesion of foreign matter to the base portion 421 and the diaphragm portion 31.

[0102] For example, if the foreign matter is liquid and the liquid adheres to the diaphragm portion 31, the surface tension of the liquid adhering to the diaphragm portion 31 may affect the deflection of the diaphragm portion 31. However, according to the first embodiment, adhesion of the liquid to the diaphragm portion 31 is suppressed, so the effect on the deflection of the diaphragm portion 31 can be reduced. Also, for example, if the foreign matter is water and the water adheres to the diaphragm portion 31, the water adhering to the diaphragm portion 31 may cause an error in the capacitance value. However, according to the first embodiment, adhesion of water to the diaphragm portion 31 is suppressed, so the occurrence of errors in the capacitance value can be reduced.

[0103] If the pressure sensor element 10 has multiple holes 63, the following problem may occur. When liquid adheres to the second substrate layer 50 and some of the openings of the multiple holes 63 are covered by the liquid, air inside the holes 63 escapes through the openings of the holes 63 that are not covered by the liquid. This may cause liquid to enter through the openings of the holes 63 that are covered by the liquid and reach the communication space 61, resulting in the liquid adhering to the diaphragm portion 31. According to the first embodiment, the communication space 61 communicates with the outside through one hole 63. In this case, when liquid adheres to the second substrate layer 50, even if the opening of one hole 63 is covered by the liquid, the air inside the hole 63 does not escape to the outside. This prevents liquid from entering the hole 63. As a result, adhesion of liquid to the diaphragm portion 31 can be prevented.

[0104] According to the first embodiment, as viewed along the stacking direction 100, the base portion 421 and the diaphragm portion 31 are located inside the first trench portion 71 and the second trench portion 72. Therefore, the first trench portion 71 and the second trench portion 72 can suppress stress generated outside the first trench portion 71 and the second trench portion 72 as viewed along the stacking direction 100 from acting on the base portion 421 and the diaphragm portion 31. This can reduce the effect of stress on the detection accuracy of the pressure sensor element 10.

[0105] According to the first embodiment, when stress generated outside the first trench portion 71 and the second trench portion 72 as viewed along the stacking direction 100 acts on the base portion 421 and the diaphragm portion 31, the transmission path of the stress meanders due to the presence of the first trench portion 71 and the second trench portion 72. This lengthens the transmission path of the stress. As a result, the transmission of the stress to the base portion 421 and the diaphragm portion 31 can be suppressed.

[0106] According to the first embodiment, it is possible to reduce the possibility of liquid entering the hole 63, compared to a configuration in which the cross-sectional area of ​​the portion of the hole 63 with the smallest cross-sectional area is larger than the area of ​​the first trench portion 71 when viewed along the stacking direction 100. Furthermore, it is possible to reduce the possibility of liquid entering the hole 63, compared to a configuration in which the cross-sectional area of ​​the portion of the hole 63 with the smallest cross-sectional area is larger than the area of ​​the second trench portion 72 when viewed along the stacking direction 100.

[0107] According to the first embodiment, it is possible to reduce the possibility of liquid entering the hole 63, compared to a configuration in which the length L1 of the longest part of the hole 63 when viewed along the stacking direction 100 is equal to or greater than the short side S1 of the first trench portion 71 that forms a rectangular ring. Also, it is possible to reduce the possibility of liquid entering the hole 63, compared to a configuration in which the length L1 of the longest part of the hole 63 when viewed along the stacking direction 100 is equal to or greater than the short side S2 of the second trench portion 72 that forms a rectangular ring.

[0108] According to the first embodiment, the possibility of liquid entering the hole 63 can be reduced compared to a configuration in which the length L2 of the longest part of the small diameter portion 632, which is the smallest part, as viewed along the stacking direction 100 is equal to or greater than the width W1 of the first trench portion 71. Furthermore, the possibility of liquid entering the hole 63 can be reduced compared to a configuration in which the length L2 is equal to or greater than the width W2 of the second trench portion 72.

[0109] Second Embodiment Fig. 16 is a schematic plan view of a pressure sensor element according to a second embodiment of the present disclosure. Fig. 17 is a schematic cross-sectional view showing the D-D cross section of Fig. 16. The pressure sensor element according to the second embodiment differs from the pressure sensor element according to the first embodiment in that it includes a convex portion 24. Differences from the first embodiment will be described below. Points in common with the pressure sensor element according to the first embodiment are given the same reference numerals, and explanations thereof will be omitted in principle, and will be described only when necessary.

[0110] 16 and 17 , in the pressure sensor element 10E according to the second embodiment, the first substrate layer 20 has nine protrusions 24 on a part of the surface facing the communication space 61. Each of the nine protrusions 24 protrudes in the stacking direction 100 toward the membrane layer 30. Each of the nine protrusions 24 is spaced apart from the membrane layer 30. The nine protrusions 24 are arranged at equal intervals along a first orthogonal direction 101 that is orthogonal to the stacking direction 100, and a second orthogonal direction 102 that is orthogonal to both the stacking direction 100 and the first orthogonal direction 101.

[0111] The shape and size of the protrusions 24 are not limited to those shown in Figures 16 and 17. The positions of the protrusions 24 are not limited to those shown in Figures 16 and 17. The number of protrusions 24 is not limited to nine. For example, as shown in Figure 18, the first substrate layer 20 may have three protrusions 24, and each of the three protrusions 24 may have a linear shape extending in the second orthogonal direction 102. Figure 18 is a schematic plan view of a modified example of the pressure sensor element according to the second embodiment of the present disclosure.

[0112] 16 to 18, the shapes of the protrusions 24 are the same, but the shapes of the protrusions 24 may be different.

[0113] For example, when pressure is applied to the pressure sensor element from the outside by pressing a mold during the manufacturing process of the pressure sensor element, the membrane layer 30, the electrode layer 40, and the second substrate layer 50 may bend, which may cause the diaphragm portion 31 and the first substrate layer 20 to come into contact with each other and remain in contact with each other.

[0114] According to the second embodiment, the first substrate layer 20 has a convex portion 24 on a portion of the surface facing the communication space 61. Therefore, when the diaphragm portion 31 and the first substrate layer 20 approach each other due to deflection of the membrane layer 30, the electrode layer 40, or the second substrate layer 50, the diaphragm portion 31 comes into contact with the convex portion 24 of the first substrate layer 20. This makes it possible to reduce the contact area between the diaphragm portion 31 and the first substrate layer 20, making it easier for the diaphragm portion 31 and the first substrate layer 20 to separate. In other words, it is possible to reduce the possibility that the diaphragm portion 31 and the first substrate layer 20, which have come into contact with each other, will remain in contact and not separate from each other.

[0115] The pressure sensor element described above can be expressed as follows.

[0116] (1) A pressure sensor element according to one aspect of the present disclosure includes: a first substrate layer; a membrane layer stacked on the first substrate layer; an electrode layer stacked on the membrane layer on a side opposite to the first substrate layer; and a second substrate layer stacked on the electrode layer on a side opposite to the membrane layer, wherein the membrane layer has a conductive diaphragm portion and a peripheral portion surrounding the diaphragm portion as viewed along a stacking direction; the first substrate layer faces the diaphragm portion of the membrane layer in the stacking direction via a communication space that communicates with the outside through at least one hole, and is joined to the peripheral portion of the membrane layer; the electrode layer has a conductive base portion facing the diaphragm portion in the stacking direction via a sealed space, and a guard portion that surrounds the base portion as viewed along the stacking direction, is spaced apart from the base portion, and is joined to the peripheral portion of the membrane layer; and the second substrate layer is joined to the electrode layer. The hole penetrates the second substrate layer, the guard portion of the electrode layer, and the peripheral portion of the membrane layer in the stacking direction, opens to the outside in the second substrate layer, and opens to the communicating space at the peripheral portion of the membrane layer.

[0117] (2) In the pressure sensor element of (1), the communication space may communicate with the outside through one of the holes.

[0118] (3) In the pressure sensor element of (1) or (2), of the second substrate layer, the guard portion of the electrode layer, and the peripheral portion of the membrane layer, at least the second substrate layer may have a first trench portion whose depth direction is the stacking direction and which opens to the outside in the second substrate layer; of the second substrate layer, the guard portion of the electrode layer, and the peripheral portion of the membrane layer, at least the peripheral portion of the membrane layer may have a second trench portion whose depth direction is the stacking direction and which opens to the communicating space in the peripheral portion of the membrane layer; when viewed along the stacking direction, the first trench portion and the second trench portion may be located outside the base portion and the diaphragm portion; when viewed along a direction perpendicular to the stacking direction, the first trench portion and the second trench portion may be aligned, and the bottom of the first trench portion may be located closer to the first substrate layer than the bottom of the second trench portion in the stacking direction.

[0119] (4) In the pressure sensor element of (3), the cross-sectional area of ​​the hole at the portion where the cross-sectional area is smallest may be smaller than the area of ​​the first trench portion or the area of ​​the second trench portion when viewed along the stacking direction.

[0120] (5) In the pressure sensor element of (3) or (4), at least one of the first trench portion and the second trench portion may be a rectangular ring when viewed along the stacking direction, and the length of the longest part of the hole when viewed along the stacking direction may be shorter than the short side of the trench portion of the first trench portion or the second trench portion that forms the rectangular ring.

[0121] (6) In any one of the pressure sensor elements (3) to (5), the length of the longest part of the hole portion, where the cross-sectional area is smallest, as viewed along the stacking direction may be shorter than the width of the first trench portion as viewed along the stacking direction or the width of the second trench portion as viewed along the stacking direction.

[0122] (7) In the pressure sensor element of any one of (3) to (6), the first substrate layer may have a convex portion on a part of the surface facing the communication space, the convex portion protruding in the stacking direction toward the membrane layer and spaced apart from the membrane layer.

[0123] Any of the various embodiments described above may be combined appropriately to achieve the effects of each of them.

[0124] While the present invention has been fully described in connection with preferred embodiments, with appropriate reference to the drawings, various changes and modifications will become apparent to those skilled in the art, and it is to be understood that such changes and modifications are included within the scope of the present invention as defined by the appended claims unless they depart therefrom.

[0125] REFERENCE SIGNS LIST 10 Pressure sensor element 20 First substrate layer 24 Convex portion 30 Membrane layer 31 Diaphragm portion 32 Peripheral portion 40 Electrode layer 41 Second insulating layer (bonding portion) 421 Base portion 422 Guard portion (bonding portion) 50 Second substrate layer 61 Communication space 62 Sealed space 63 Hole portion 71 First trench portion 72 Second trench portion 100 Stacking direction

Claims

1. A semiconductor device comprising: a first substrate layer; a membrane layer laminated on the first substrate layer; an electrode layer laminated on the membrane layer on a side opposite to the first substrate layer; and a second substrate layer laminated on the electrode layer on a side opposite to the membrane layer, wherein the membrane layer has a conductive diaphragm portion and a peripheral portion surrounding the diaphragm portion as viewed along a stacking direction, the first substrate layer faces the diaphragm portion of the membrane layer in the stacking direction via a communication space that communicates with the outside through at least one hole portion, and is joined to the peripheral portion of the membrane layer, the electrode layer has a conductive base portion facing the diaphragm portion in the stacking direction via an enclosed space, and a guard portion that surrounds the base portion as viewed along the stacking direction, is spaced from the base portion, and is joined to the peripheral portion of the membrane layer, and the second substrate layer is joined to the electrode layer, The hole portion is a pressure sensor element that penetrates the second substrate layer, the guard portion of the electrode layer, and the peripheral portion of the membrane layer in the stacking direction, opens to the outside in the second substrate layer, and opens to the communicating space at the peripheral portion of the membrane layer.

2. The pressure sensor element according to claim 1, wherein the communication space communicates with the outside through one of the holes.

3. A pressure sensor element as described in claim 1 or 2, wherein of the second substrate layer, the guard portion of the electrode layer, and the peripheral portion of the membrane layer, at least the second substrate layer has a first trench portion whose depth direction is the stacking direction and which opens to the outside in the second substrate layer, and of the second substrate layer, the guard portion of the electrode layer, and the peripheral portion of the membrane layer, at least the peripheral portion of the membrane layer has a second trench portion whose depth direction is the stacking direction and which opens to the communicating space in the peripheral portion of the membrane layer, when viewed along the stacking direction, the first trench portion and the second trench portion are located outside the base portion and the diaphragm portion, and when viewed along a direction perpendicular to the stacking direction, the first trench portion and the second trench portion are aligned, and in the stacking direction, a bottom of the first trench portion is located closer to the first substrate layer than a bottom of the second trench portion.

4. A pressure sensor element as described in claim 3, wherein the cross-sectional area of ​​the hole at the portion having the smallest cross-sectional area is smaller than the area of ​​the first trench portion or the area of ​​the second trench portion when viewed along the stacking direction.

5. A pressure sensor element as described in claim 3 or 4, wherein at least one of the first trench portion or the second trench portion has a rectangular ring shape when viewed along the stacking direction, and the length of the longest part of the hole when viewed along the stacking direction is shorter than the short side of the trench portion of the first trench portion or the second trench portion that constitutes the rectangular ring shape.

6. A pressure sensor element described in any one of claims 3 to 5, wherein the length of the longest part of the hole portion, where the cross-sectional area is the smallest, when viewed along the stacking direction is shorter than the width of the first trench portion when viewed along the stacking direction or the width of the second trench portion when viewed along the stacking direction.

7. A pressure sensor element as claimed in any one of claims 3 to 6, wherein the first substrate layer has a convex portion on a part of its surface facing the communicating space, protruding in the stacking direction towards the membrane layer and spaced apart from the membrane layer.

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