Gas sensor

Abstract

A gas sensor (100) is provided with a laminate (11) in which electrode layers (31, 32L) and insulating layers (24L) are alternately laminated, and a sensing film (40) that reacts with a gas to be measured, in which a recess (11A1) that is recessed in the lamination direction is formed in the laminate (11), and the recess (11A1) is provided with a side surface (11C) that includes the end surfaces of the electrode layers (31, 32L) and the end surfaces of the insulating layers (24L). The sensing film (40) is in contact with one insulating layer (24L) on the side surface (11C) of the recess (11A1) and at least one pair of electrode layers (31, 32L) sandwiching the one insulating layer (24L).

Description

Technical Field

[0001] The present disclosure relates to gas sensors. Background Art

[0002] Patent Document 1 describes a sensor technology that is known for its ability to detect specific substances by forming a first Au layer on a silicon substrate and separating a second Au layer from the first Au layer using Al2O3. This creates a nanogap with a thickness equivalent to that of the Al2O3. This sensor can detect specific substances by observing changes in electrical properties across the nanogap when a solution is injected into the gap.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2006-234799 Summary of the Invention

[0006] Problems to be solved by the invention

[0007] The structure disclosed in Patent Document 1 aims to improve the detection sensitivity of specific substances. Therefore, a sensor can be constructed, for example, by providing a sensing layer (sensing film) that contacts two electrode layers (metal layers) and an insulating layer therebetween and reacts with the specific substance. However, in this case, the sensing layer may have irregularities or bends that mimic the shapes of the electrode and insulating layers, potentially causing cracks or breaks (referred to as disconnections) in these irregularities.

[0008] The present disclosure is a technology developed based on the above-described circumstances, and one object of the present disclosure is to provide a gas sensor capable of improving detection sensitivity. Another object of the present disclosure is to provide a gas sensor capable of suppressing disconnection.

[0009] Means for solving problems

[0010] The gas sensor disclosed herein comprises: a laminated body formed by alternating electrode layers and insulating layers; and a sensitive film that reacts with a gas to be measured. The laminated body has a recessed portion that is recessed in the stacking direction, the recess having side surfaces including end surfaces of the electrode layers and end surfaces of the insulating layers. The sensitive film is in contact with one insulating layer on the side surface of the recess and at least one pair of electrode layers sandwiching the insulating layer.

[0011] Effects of the Invention

[0012] According to the present disclosure, a gas sensor capable of improving detection sensitivity and preventing disconnection can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a plan view schematically showing the gas sensor device according to the first embodiment.

[0014] Figure 2 It is a diagram showing a cross-sectional structure of a portion of a gas sensor.

[0015] Figure 3 This is an enlarged cross-sectional view of the vicinity of one inclined surface of the laminate.

[0016] Figure 4 It is a plan view showing a partially enlarged surface of the laminate.

[0017] Figure 5 This is a plan view schematically showing the gas sensor device according to the second embodiment.

[0018] Figure 6 It is a diagram showing a cross-sectional structure of a portion of a gas sensor.

[0019] Figure 7 It is a top view showing the recessed portion of the third embodiment.

[0020] Figure 8 It is a top view showing the recessed portion of the fourth embodiment.

[0021] Figure 9 It is a top view showing the recessed portion of the fifth embodiment. DETAILED DESCRIPTION

[0022] First, embodiments of the present disclosure will be described.

[0023] (1) The gas sensor disclosed herein comprises: a laminated body formed by alternately laminating electrode layers and insulating layers; and a sensitive film that reacts with a gas to be measured, wherein the laminated body has a recessed portion that is recessed in the lamination direction, the recess having side surfaces including end surfaces of the electrode layers and end surfaces of the insulating layers, and the sensitive film is in contact with one insulating layer on the side surface of the recess and at least one pair of electrode layers sandwiching the insulating layer.

[0024] (2) In the gas sensor described in (1), a side surface of the recess may be inclined with respect to the stacking direction.

[0025] (3) In the gas sensor described in (1) or (2), the recess may include a bottom surface formed by a surface of the electrode layer perpendicular to the stacking direction, and the sensitive film may be in contact with the bottom surface of the recess.

[0026] (4) In the gas sensor described in any one of (1) to (3), the outer shape of the recessed portion may be a regular hexagon, a circle, an equilateral triangle, or a rhombus when viewed from above.

[0027] (5) In the gas sensor according to any one of (1) to (4), the plurality of recesses may be arranged in a closest-packed manner in a plan view.

[0028] <Implementation Method 1>

[0029] pass Figure 1 Embodiment 1 of the present disclosure is described below. In this embodiment, a gas sensor 100 capable of detecting a specific gas (measured gas) is exemplified. Figure 2 and Figure 3 In the embodiment, the Z direction is set as the stacking direction, and the X direction perpendicular to the Z direction is set as the horizontal direction. Figure 1 and Figure 4 The front side of the paper, Figure 2 and Figure 3 The upper side of the paper in FIG. 1 is defined as the surface side of the gas sensor 100 (the upper side in the stacking direction). Figure 1 and Figure 4 On the inside of the paper, Figure 2 and Figure 3 The lower side of the paper in FIG. 1 is defined as the back side (the lower side in the stacking direction) of the gas sensor 100 .

[0030] like Figure 1 As shown, gas sensor 100 includes a flat substrate 10, a laminate 11 stacked on the surface of substrate 10, and first and second wirings 15 and 16 disposed on the surface of substrate 10 and connected to laminate 11. Substrate 10 is made of silicon, for example. Gas sensor 100, together with power supply 2 and ammeter 3, constitutes gas sensor device 1. Power supply 2 is connected to first wiring 15 and ammeter 3. Ammeter 3 is connected to second wiring 16.

[0031] like Figure 2 As shown, the stacked body 11 comprises a plurality of electrode layers 31, 32L, and 32R and a plurality of insulating layers 21, 22, 23, 24L and 24R, and 25L and 25R stacked in the stacking direction (vertical direction). Specifically, the first insulating layer 21, the second insulating layer 22, and the third insulating layer 23 are stacked in this order on the surface of the substrate 10. On the surface of the third insulating layer 23, the first electrode layer 31, the fourth insulating layers 24L and 24R, the second electrode layers 32L and 32R, and the fifth insulating layers 25L and 25R are stacked in this order. From the third insulating layer 23 to the fifth insulating layer 25L and 25R, the plurality of insulating layers 23, 24L and 24R, 25L and 25R, and the plurality of electrode layers 31, 32L, and 32R are stacked alternately in the stacking direction.

[0032] The fourth insulating layers 24L and 24R, the second electrode layers 32L and 32R, and the fifth insulating layers 25L and 25R, respectively, include one layer 24L, 32L, and 25L positioned on the left side of the drawing relative to a first horizontal plane 11B, described later, and another layer 24R, 32R, and 25R positioned on the right side of the drawing relative to the first horizontal plane 11B. The first electrode layer 31, the fourth insulating layer 24L on the left side, and the second electrode layer 32L on the left side constitute one main body layer portion 12L. Furthermore, the first electrode layer 31, the fourth insulating layer 24R on the right side, and the second electrode layer 32R on the right side constitute another main body layer portion 12R.

[0033] In the stacking direction, the distance between the first electrode layer 31 and the second electrode layer 32L on the left (the thickness of the fourth insulating layer 24L on the left), and the distance between the first electrode layer 31 and the second electrode layer 32R on the right (the thickness of the fourth insulating layer 24R on the right) are both in the nanometer range. These distances can be, for example, greater than 1 nm and less than 1000 nm, or less than 100 nm, or even tens of nm. Figure 1 The first wiring 15 is shown. The second wiring 16 is connected to each of the second electrode layers 32L and 32R.

[0034] The materials of the electrode layers 31, 32L, and 32R, and the wirings 15 and 16 are not particularly limited, as long as they are conductive. For example, one or more metals such as aluminum, copper, gold, and platinum can be used. The materials of the insulating layers 21, 22, 23, 24L and 24R, and 25L and 25R are not particularly limited, as long as they are non-conductive. Compounds such as SiO2 and Si3N4 can be used. A heater 50 capable of heating the stack 11 is provided within the second insulating layer 22.

[0035] The surface 11A of the stacked body 11 includes a first horizontal surface 11B extending perpendicularly (horizontally) to the stacking direction; second horizontal surfaces 11D and 11F extending perpendicularly to the stacking direction and located above the first horizontal surface 11B; and inclined surfaces 11C and 11E, which are connected to the first horizontal surface 11B and the second horizontal surfaces 11D and 11F, respectively, and inclined with respect to the stacking direction. The first horizontal surface 11B and the inclined surfaces 11C and 11E form a recessed portion 11A1 in the stacked body 11, which is recessed from the second horizontal surfaces 11D and 11F in the stacking direction. The inclined surfaces 11C and 11E and the second horizontal surfaces 11D and 11F each include one surface 11C and 11D located on the left side of the paper relative to the first horizontal surface 11B, and another surface 11E and 11F located on the right side of the paper relative to the first horizontal surface 11B.

[0036] On the inclined surface (side surface) 11C on the left side of the recessed portion 11A1, the first electrode layer 31 and the left second electrode layer 32L form a pair of electrode layers, sandwiching the left fourth insulating layer (single insulating layer) 24L. Similarly, on the inclined surface (side surface) 11E on the right side of the recessed portion 11A1, the first electrode layer 31 and the right second electrode layer 32R form a pair of electrode layers, sandwiching the right fourth insulating layer (single insulating layer) 24R.

[0037] The first electrode layer 31 includes a thin portion 36, thick portions 38R and 38L thicker than the thin portion 36, and graduated layer portions 37R and 37L arranged between the thin portion 36 and the thick portions 38R and 38L, with thickness gradually changing in the horizontal direction. The thick portions 38R and 38L are thicker than the second electrode layers 32R and 32L. The graduated layer portions 37R and 37L and the thick portions 38R and 38L each include one layer portion 37L and 38L arranged on the left side of the paper relative to the thin portion 36, and another layer portion 37R and 38R arranged on the right side of the paper relative to the thin portion 36. The left fourth insulating layer 24L is laminated on the surface 38LA of the left thick portion 38L. Similarly, the right fourth insulating layer 24R is laminated on the surface 38RA of the right thick portion 38R.

[0038] First horizontal plane 11B is a surface of first electrode layer 31 perpendicular to the stacking direction and serves as the surface (upper surface) of thin-film portion 36. First horizontal plane 11B also forms the bottom surface of recess 11A1. Second horizontal planes 11D and 11F serve as the surfaces (upper surfaces) of fifth insulating layers 25L and 25R, respectively.

[0039] Inclined surfaces 11C and 11E are provided as side surfaces of the recessed portion 11A1 and are inclined relative to the stacking direction. Figure 3 As shown, one inclined surface 11C is a side surface of the first electrode layer 31. It is formed by connecting the side surface 37LA of the left-side gradient layer portion 37L, the side surface 24LA of the left-side fourth insulating layer 24L, the side surface 32LA of the left-side second electrode layer 32L, and the side surface 25LA of the left-side fifth insulating layer 25. The side surfaces 37LA, 24LA, 32LA, and 25LA of each layer are sometimes referred to as end surfaces. The left side surface (inclined surface 11C) of the recessed portion 11A1 includes the end surfaces 37LA and 32LA of the electrode layers (the first electrode layer 31 and the left-side second electrode layer 32L) and the end surface 24LA of the insulating layer (the left-side fourth insulating layer 24L). These end surfaces 37LA, 24LA, and 32LA constitute the side surfaces (end surfaces) of one main body layer portion 12L.

[0040] The first electrode layer 31 is the lowest layer of the main body layer portions 12L and 12R and is a specific electrode layer having a first horizontal surface 11B connected to the inclined surfaces 11C and 11E. As a specific electrode layer, the first electrode layer 31 has a side surface 37LA. This side surface 37LA is the side surface 37LA of the left-side gradient layer portion 37L. This side surface 37LA rises obliquely from its first horizontal surface 11B and forms part of one inclined surface 11C. The angle θ formed by the corner 39 between the first horizontal surface 11B and the one inclined surface 11C (or the side surface 37LA) is set to an obtuse angle greater than 90 degrees. The structure of the one inclined surface 11C described above is also applied to the other inclined surface 11E (left-right symmetric).

[0041] like Figure 2 and Figure 3 As shown, the gas sensor 100 includes a sensitive film 40 that contacts the bottom surface 11B of the recess 11A1, the side surfaces 11C and 11E of the recess 11A1, and the outer side surfaces (second horizontal surfaces 11D and 11F) of the recess 11A1. The sensitive film 40 contacts the entire surface 11A of the laminate 11. On the side surfaces 11C and 11E of the recess 11A1, the sensitive film 40 contacts the side surface 24LA of one insulating layer 24L (or 24R) and the side surfaces 37LA and 32LA of at least one pair of electrode layers 31 and 32L (or 31 and 32R) sandwiching the side surface 24LA. The sensitive film 40 contacts the side surface 37LA of the left-side gradient layer 37L (the portion of the inclined surface 11C that is continuous with the first horizontal surface 11B). The sensitive film 40 contacts the corner 39. Furthermore, the sensitive film 40 contacts the second horizontal surface 11D from the inclined surface 11C. This structure is also provided in the other inclined surface 11E in the same manner (left-right symmetrical).

[0042] Figure 4 is a partially enlarged top view of the surface 11A of the stack 11, omitting the illustration of the sensitive film 40. The outer shape of the recess 11A1 is a regular hexagon when viewed from above. Specifically, the recess 11A1 includes a bottom surface 11B, which is a regular hexagon when viewed from above, and six inclined surfaces 11C, 11C1, 11C2, 11E, 11E1, and 11E2, which rise from the six ends of the bottom surface 11B and extend obliquely with respect to the stacking direction. Inclined surfaces 11C, 11E, 11C1, 11E1, and 11C2, 11E2 are arranged at both ends of the bottom surface 11B and form pairs. Upper end portions G1 , G2 , G3 , G4 , G5 , and G6 of the inclined surfaces 11C, 11C1 , 11C2 , 11E, 11E1 , and 11E2 define the outer shape of the recess 11A1 , and are generally regular hexagonal in a plan view.

[0043] On the surface 11A of the laminate 11, a plurality of recesses 11A1 are arranged in a closest-packed pattern when viewed from above. In this embodiment, they are arranged in a honeycomb pattern when viewed from above. Specifically, the plurality of recesses 11A1 are arranged so that the distance between adjacent recesses 11A1 is equal to the distance between other adjacent recesses 11A1. For example, the distance L1 between a recess 11A1 located slightly above the center of the paper and the recess 11A1 located below it (slightly below the center of the paper) is equal to the distance L2 between a recess 11A1 located slightly above the center of the paper and the recess 11A1 located to its lower right (to the right of the center of the paper).

[0044] The sensitive film 40 contacts the recesses 11A1 and the surfaces therebetween (second horizontal surfaces 11D, 11F, etc.), and the first horizontal surface 11B and the inclined surfaces 11C, 11C1, 11C2, 11E, 11E1, and 11E2 of the recesses 11A1.

[0045] The sensitive film 40 is configured to react with a specific gas (the gas being measured) and change its electrical properties (e.g., resistance). The material for the sensitive film 40 can be appropriately selected based on the gas to be detected and is not particularly limited. For example, an oxide semiconductor film can be used. Examples of oxide semiconductor films include ZnO, SnO2, WO3, In2O3, TiO2, and V2O5. In the gas sensor 100, when the specific gas reacts with the sensitive film 40 and changes its resistance, the current value of the ammeter 3 connected to the power supply 2 in the gas sensor device 1 changes. This allows the gas sensor device 1 to detect the specific gas.

[0046] In addition, the manufacturing method of the gas sensor 100 is not particularly limited. For example, in the process of forming the stacked body 11, Figure 2 As shown, ion etching may be performed from the surface side of the fifth insulating layers 25L and 25R to form the inclined surfaces 11C, 11E and the first horizontal surface 11B.

[0047] Next, the effects of this embodiment will be described. Gas sensor 100 of this embodiment includes a stacked body 11 formed by alternating electrode layers 31 and 32L and insulating layers 24L, and a sensitive film 40 that reacts with a target gas. Stacked body 11 includes a recessed portion 11A1 that is recessed in the stacking direction. Recessed portion 11A1 includes side surfaces 11C that include the end surfaces of electrode layers 31 and 32L and the end surface of insulating layer 24L. Sensitive film 40 is in contact with one insulating layer 24L and at least one pair of electrode layers 31 and 32L sandwiching the insulating layer 24L, located on side surfaces 11C of recessed portion 11A1.

[0048] According to this gas sensor 100, the pair of electrode layers 31 and 32L are insulated by a single insulating layer 24R, and the sensitive film 40 is in contact with the pair of electrode layers 31 and 32L. Therefore, the target gas reacts with the sensitive film 40, causing, for example, changes in electrical properties within the sensitive film 40. This allows for highly sensitive and selective detection of the target gas passing through the two electrode layers 31 and 32L. Furthermore, the sensitive film 40 contacts the insulating layer 24L on the side surface 11C of the recess 11A1, as well as at least one pair of electrode layers 31 and 32L sandwiching the insulating layer 24L. This increases the contact area with the sensitive film 40, providing an anchoring effect and enabling a gas sensor 100 with enhanced detection sensitivity. For example, if multiple electrode layers 31 and 32L are arranged on the surface of the insulating layer 24R and the sensitive film 40 contacts them, there is a risk of creating irregularities in the sensitive film 40 that mimic the shapes of the electrode layers 31 and 32L, resulting in disconnection in these irregularities. However, according to the gas sensor 100 described above, the sensitive film 40 contacts the side surface 11C of the recessed portion 11A1, which includes the end surfaces of the electrode layers 31 and 32L and the end surface of the insulating layer 24R, and the pair of electrode layers 31 and 32L. Therefore, the generation of the above-described unevenness in the sensitive film 40 can be avoided. Consequently, disconnection can be suppressed.

[0049] The side surfaces 11C of the recessed portion 11A1 are inclined with respect to the stacking direction.

[0050] This gas sensor 100 increases the contact area with the sensitive film 40 compared to a case where the side surfaces of the recess are not inclined but extend in the stacking direction (where the side surfaces of the recess are perpendicular to the surface of the electrode layer), thereby improving detection sensitivity. Furthermore, the sensitive film 40 that contacts the side surfaces 11C of the recess 11A1 and the electrode layers 31 and 32L can be prevented from being bent at right angles. This prevents disconnection.

[0051] The recessed portion 11A1 includes a bottom surface 11B formed by a surface of the electrode layer 31 perpendicular to the stacking direction, and the sensitive film 40 is in contact with the bottom surface 11B of the recessed portion 11A1 .

[0052] According to such a gas sensor 100 , the contact area between the electrode layers 31 and 32L and the sensitive film 40 can be increased, thereby improving the detection sensitivity.

[0053] The outer shape of the recess 11A1 is a regular hexagon in a plan view.

[0054] According to such gas sensor 100 , the distance (area) between each side of the regular hexagon forming the outer shape of recess 11A1 in plan view and the sensitive film 40 is equal, so that current can flow evenly along each side.

[0055] The plurality of recessed portions 11A1 are arranged in a closest-packed manner in a plan view.

[0056] According to this gas sensor 100, when electricity is applied to the electrode layers 31 and 32L, current easily flows evenly through each recess 11A1. Furthermore, because the plurality of recesses 11A1 are arranged differently in each row, the plurality of recesses 11A1 can be appropriately arranged in a single gas sensor 100, further increasing the contact area with the sensitive film 40.

[0057] <Implementation Method 2>

[0058] Then, through Figure 5 Embodiment 2 of the present disclosure will be described below. In this embodiment, the same reference numerals are used for the same portions as those in the above embodiment, and redundant descriptions of the structure, operation, and effects will be omitted.

[0059] like Figure 5 As shown, gas sensor 200 includes a first wiring 215 and a second wiring 216 connected to stacked body 211. First wiring 215 branches into a back wiring 215A and a front wiring 215B. Similarly, second wiring 216 branches into a back wiring 216A and a front wiring 216B. Gas sensor 200, together with power supply 2 and ammeter 3, constitutes gas sensor device 201.

[0060] like Figure 6 As shown, the stacked body 211 includes a plurality of electrode layers 31, 32L and 32R, 233L and 233R, 234L and 234R, and a plurality of insulating layers 21, 22, 23, 24L and 24R, 25L and 25R, 226L and 226R, 227L and 227R stacked in the stacking direction (vertical direction). The third electrode layer 233L on the left, the sixth insulating layer 226L on the left, the fourth electrode layer 234L on the left, and the seventh insulating layer 227L on the left are stacked in this order on the surface of the fifth insulating layer 25L on the left. The third electrode layer 233R on the right, the sixth insulating layer 226R on the right, the fourth electrode layer 234R on the right, and the seventh insulating layer 227R on the right are stacked in this order on the surface of the fifth insulating layer 25R on the right.

[0061] The first electrode layer 31 is connected to Figure 1 The backside wiring 215A of the first wiring 215 is shown. The backside wiring 216A of the second wiring 216 is connected to the second electrode layers 32L and 32R. The frontside wiring 215B of the first wiring 215 is connected to the third electrode layers 233L and 233R. The frontside wiring 216B of the second wiring 216 is connected to the fourth electrode layers 234L and 234R.

[0062] On the surface 211A of the stack 211, the first horizontal surface 11B serves as the surface (upper surface) of the thin layer portion 36. An inclined surface 211C is formed by connecting the side surfaces of the graded layer portion 37L, the fourth insulating layer 24L, the second electrode layer 32L, the fifth insulating layer 25L, the third electrode layer 233L, the sixth insulating layer 226L, the fourth electrode layer 234L, and the seventh insulating layer 227L. Another inclined surface 211E has the same structure (bilaterally symmetrical) as the inclined surface 211C. The first horizontal surface 11B and the inclined surfaces 211C and 211E form a recessed portion 211A1 in the stack 211, which is recessed from the second horizontal surfaces 211D and 211F in the stacking direction. The second horizontal surfaces 211D and 211F serve as the surfaces (upper surfaces) of the seventh insulating layers 227L and 227R, respectively. The sensing film 240 contacts the inclined surfaces 211C and 211E from the first horizontal surface 211B, and further contacts the second horizontal surfaces 211D and 211F from the inclined surfaces 211C and 211E.

[0063] <Implementation Method 3>

[0064] Then, through Figure 7 Embodiment 3 of the present disclosure will be described. This embodiment changes the surface shape of the laminate 11 of Embodiment 1. Reference numerals corresponding to those of Embodiment 1 are used with the tens digit of the numerals changed from 1 to 5, and redundant descriptions of the structure, operation, and effects are omitted.

[0065] like Figure 7 As shown, the surface 51A of the stacked body 51 includes a first horizontal surface 51B extending perpendicularly (horizontally) to the stacking direction, a second horizontal surface 51D located above the first horizontal surface 51B, and an inclined surface 51C inclined with respect to the stacking direction. Inclined surface 51C and second horizontal surface 51B form a bottomed recess 5D. The outer shape of recess 5D is circular when viewed from above.

[0066] <Implementation Method 4>

[0067] Then, through Figure 8 Embodiment 4 of the present disclosure will be described. This embodiment changes the surface shape of the laminate 11 of Embodiment 1. Reference numerals corresponding to those of Embodiment 1 are used with the tens digit of the numerals changed from 1 to 6, and redundant descriptions of the structure, operation, and effects are omitted.

[0068] like Figure 8As shown, the surface 61A of the stacked body 61 includes a first horizontal surface 61B extending perpendicularly (horizontally) to the stacking direction, a second horizontal surface 61D located above the first horizontal surface 61B, and an inclined surface 61C inclined with respect to the stacking direction. Inclined surface 61C and second horizontal surface 61B form a bottomed recessed portion 6D. The outer shape of recessed portion 6D is an equilateral triangle when viewed from above.

[0069] <Implementation Method 5>

[0070] Then, through Figure 9 Embodiment 5 of the present disclosure will be described. This embodiment changes the surface shape of the laminate 11 of Embodiment 1. Reference numerals corresponding to those of Embodiment 1 are used with the tens digit of the numerals changed from 1 to 7, and redundant descriptions of the structure, operation, and effects are omitted.

[0071] like Figure 9 As shown, surface 71A of stacked body 71 includes a first horizontal surface 71B extending perpendicularly (horizontally) to the stacking direction, a second horizontal surface 71D located above first horizontal surface 71B, and an inclined surface 71C inclined with respect to the stacking direction. Inclined surface 71C and second horizontal surface 71B form a bottomed recessed portion 7D. The outer shape of recessed portion 7D is rhombus-shaped when viewed from above.

[0072] <Other Implementation Methods>

[0073] The present disclosure is not limited to the embodiments described above and illustrated in the drawings. For example, the following embodiments are also included in the technical scope of the present disclosure. In addition, various modifications other than those described below can be made without departing from the spirit of the present disclosure.

[0074] (1) In addition to the above-described embodiments, the structure of the laminate can be modified as appropriate. The laminate may include at least a first electrode layer, an insulating layer laminated on the first electrode layer, and a second electrode layer laminated on the insulating layer. In such a structure, the upper surface of the second electrode layer may be in contact with the sensitive film.

[0075] (2) In addition to the above-described embodiments, the structure of the sensitive film may be modified as appropriate. The sensitive film may be in contact with the first horizontal surface and the inclined surface, but not in contact with the second horizontal surface. Furthermore, the sensitive film may be in contact with a portion of the first horizontal surface and an inclined surface connected to a portion of the first horizontal surface.

[0076] (3) The structure of the recess can be modified as appropriate. The side surface (inclined surface) of the recess may extend in the direction along the stacking direction. The planar shape of the recess is not limited to a regular hexagon, regular triangle, rhombus, or circle, but may also be other triangles, quadrilaterals, or other polygons. In addition, a structure may be provided in which a plurality of recesses extending in one direction are arranged on the surface of the laminate so as to appear like slits when viewed from above.

[0077] (4) The structure of the wiring can be changed appropriately. In the above embodiment, the wiring is connected to both sides of the laminate (on the Figure 1 The wiring is connected to the left and right sides of the paper in the figure, but is not limited to this. For example, the wiring may be connected to the front side of the stack (on the left and right sides of the paper). Figure 1 The wiring is done by connecting the cables (the lower side of the paper).

[0078] (5) In the gas sensor device, the device for measuring electrical characteristics is not limited to an ammeter for measuring current, and a measuring device for measuring various electrical characteristics, such as a voltmeter and an ohmmeter, may also be used.

[0079] Description of Reference Numerals

[0080] 11, 211…Layered structure, 11A1, 211A1…Recessed portion, 11B…First horizontal surface (bottom surface), 11C, 11E, 211C, 211E…Inclined surface (side surface), 24L, 24R, 224L, 224R…Fourth insulating layer (first insulating layer), 31…First electrode layer, 32L, 32R…Second electrode layer, 40, 240…Sensing film, 100, 200…Gas sensor

Claims

1. A gas sensor comprising: A laminated body composed of alternately stacked electrode layers and insulating layers; and The sensing membrane reacts with the gas being measured. in, A recessed portion recessed in the stacking direction is formed on the stacked body. The recess has a side surface including an end surface of the electrode layer and an end surface of the insulating layer. The sensitive film is in contact with an insulating layer on a side surface of the recess and at least a pair of electrode layers sandwiching the insulating layer.

2. The gas sensor according to claim 1, wherein The side surfaces of the recess are inclined with respect to the stacking direction.

3. The gas sensor according to claim 1 or 2, wherein: The recess has a bottom surface formed by a surface of the electrode layer perpendicular to the stacking direction. The sensing film contacts the bottom surface of the recess.

4. The gas sensor according to claim 1 or 2, wherein: The outer shape of the concave portion is a regular hexagon, a circle, a regular triangle or a rhombus when viewed from above.

5. The gas sensor according to claim 1 or 2, wherein: The plurality of recesses are arranged in a closest-packed manner in a plan view.

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