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EP-4386368-B1 - CAPACITIVE HYDROGEN SENSOR

EP4386368B1EP 4386368 B1EP4386368 B1EP 4386368B1EP-4386368-B1

Inventors

  • HAYASHI, YUMI

Dates

Publication Date
20260506
Application Date
20230824

Claims (13)

  1. A sensor (110), comprising: a base (40) including a first region (41) and a second region (42); a fixed electrode (55) fixed to the first region (41); a first fixed portion (21) fixed to the second region (42); a first support portion (31s) connected to the first fixed portion (21), the first support portion (31s) including a first support layer (31L) and a first layer (31) fixed to the first support layer (31L),; and a movable portion (30M) supported by the first support portion (31s), a first gap (G1) being provided between the fixed electrode (55) and the movable portion (30M); characterized in that : the first layer (31) comprises a metal oxide configured to be reduced by a detection target gas around the first layer (31), the metal oxide comprises oxygen and at least one metal selected from the group consisting of Pt, Pd and Ti.
  2. The sensor (110) according to claim 1, wherein the detection target gas includes hydrogen.
  3. The sensor (110) according to claim 1 or 2, wherein a concentration of the detection target gas in a first state is higher than a concentration of the detection target gas in a second state, and a first distance between the fixed electrode (55) and the movable portion (30M) in the first state is longer than a second distance between the fixed electrode (55) and the movable portion (30M) in the second state.
  4. The sensor (110) according to claim 1 or 2, wherein a concentration of the detection target gas in a first state is higher than a concentration of the detection target gas in a second state, and a first volume of the first layer (31) in the first state is smaller than a second volume of the first layer (31) in the second state.
  5. The sensor (110) according to claim 1 or 2, wherein a concentration of the detection target gas in a first state is higher than a concentration of the detection target gas in a second state, the movable portion (30M) comprises a movable electrode (35), and a first electrical capacitance between the fixed electrode (55) and the movable electrode (35) in the first state is smaller than a second electrical capacitance between the fixed electrode (55) and the movable electrode (35) in the second state.
  6. The sensor (110) according to claim 5, further comprising: a controller (70) configured to detect the first electrical capacitance and the second electrical capacitance.
  7. The sensor (110) according to any one of claims 1-6, wherein the first support portion (31s) further includes a first conductive member (31h), and a temperature of the first support portion (31s) can be increased by a current flowing through the first conductive member (31h).
  8. The sensor (110) according to any one of claims 1-7, wherein the first support layer (31L) includes silicon oxide.
  9. The sensor (110) according to any one of claims 1-8, wherein the first support layer (31L) is provided between the base (40) and the first layer (31), and a second gap (G2) is provided between the base (40) and the first support layer (31L).
  10. The sensor (110) according to claim 9, further comprising: a first connecting portion (31c), a part of the first connecting portion (31c) being connected to the first support portion (31s), another part of the first connecting portion (31c) being connected to the movable portion (30M), and a third gap (G3) being provided between the base (40) and the first connecting portion (31c).
  11. The sensor (110) according to claim 10, wherein the first connecting portion (31c) has a meandering structure.
  12. The sensor (110) according to any one of claims 1-11, further comprising: a second fixed portion (22); and a second support portion (32s), the base (40) further including a third region (43), the first region (41) being between the second region (42) and the third region (43), the second fixed portion (22) being fixed to the third region (43), the second support portion (32s) being connected to the second fixed portion (22), the second support portion (32s) including a second support layer (32L) and a second layer (32) fixed to the second support layer (32L), the second layer (32) including at least one metal selected from the group consisting of Pt, Pd and Ti, and oxygen, and the movable portion (30M) being provided between the first support portion (31s) and the second support portion (32s) and being further supported by the second support portion (32s).
  13. The sensor (110) according to claim 12, further comprising: a second connecting portion (32c), a part of the second connecting portion (32c) being connected to the second support portion (32s), another part of the second connecting portion (32c) being connected to the movable portion (30M), and a gap (G5) being provided between the base (40) and the second connecting portion (32c).

Description

FIELD Embodiments described herein relate generally to a sensor and a sensor system. BACKGROUND For example, there are sensors that apply MEMS structures. High detection sensitivity is desired in the sensor. US2022/018820A1 discloses a sensor including a base body and a first sensor part. The first sensor part includes fixed and movable electrode members, and first and second support members. The fixed electrode member includes a fixed electrode fixed to the base body. The movable electrode member includes a movable electrode. The movable electrode member includes first and second movable portions, and a third movable portion between the first and second movable portions. The first support member is fixed to the base body and connected with the first movable portion. The second support member is fixed to the base body and connected with the second movable portion. The first and second support members support the movable electrode member to provide a first gap between the fixed and movable electrode members. The fixed electrode member includes first, second, and third fixed electrode portions facing the movable portion. US2022/082522A1 discloses a sensor including a sensor part and a first circuit. The sensor part includes a base body, a fixed electrode fixed to the base body, a supporter fixed to the base body, and a movable part supported by the supporter. The movable part includes a movable region including a movable electrode facing the fixed electrode, and a first support region provided between the movable region and the supporter. The first support region includes a first electrode and a second electrode insulated from the first electrode. The first circuit is configured to perform a first operation of applying a voltage between the first electrode and the second electrode. KR101550173B1 discloses a hydrogen detection sensor. The hydrogen detection sensor includes a first electrode layer disposed on the surface of a substrate, a second electrode layer disposed on the upper portion of the first electrode layer, an insulating layer disposed between the first electrode layer and the second electrode layer, and a capacitance measurement device for measuring changes in capacitance of the insulating layer. The second electrode layer includes a metal catalyst capable of dissociating hydrogen molecules into hydrogen atoms. The insulating layer is formed of an insulating material capable of being reduced by reacting with the hydrogen atoms. SUMMARY The invention provides a sensor of claim 1. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic cross-sectional view illustrating a sensor according to a first embodiment;FIG. 2 is a graph illustrating characteristics of the sensor according to the first embodiment;FIGS. 3A to 3C are schematic cross-sectional views illustrating a method for manufacturing the sensor according to the first embodiment;FIGS. 4A to 4C are schematic cross-sectional views illustrating the method for manufacturing the sensor according to the first embodiment; andFIGS. 5A to 5C are schematic cross-sectional views illustrating the method for manufacturing the sensor according to the first embodiment. DETAILED DESCRIPTION According to one embodiment, a sensor includes a base, a base including a first region and a second region, a fixed electrode fixed to the first region, a first fixed portion fixed to the second region, a first support portion, and a movable portion. The first support portion is connected to the first fixed portion. The first support portion includes a first support layer and a first layer fixed to the first support layer. The first layer includes at least one metal selected from the group consisting of Pt, Pd and Ti, and oxygen. The movable portion is supported by the first support portion. A first gap is provided between the fixed electrode and the movable portion. Various embodiments are described below with reference to the accompanying drawings. The drawings are schematic and conceptual; and the relationships between the thickness and width of portions, the proportions of sizes among portions, etc., are not necessarily the same as the actual values. The dimensions and proportions may be illustrated differently among drawings, even for identical portions. In the specification and drawings, components similar to those described previously or illustrated in an antecedent drawing are marked with like reference numerals, and a detailed description is omitted as appropriate. First Embodiment FIG. 1 is a schematic cross-sectional view illustrating a sensor according to a first embodiment. As shown in FIG. 1, a sensor 110 according to the embodiment includes a base 40, a fixed electrode 55, a first fixed portion 21, a first support portion 31s and a movable portion 30M. The base 40 includes a first region 41 and a second region 42. The base 40 may be, for example, a silicon substrate. The fixed electrode 55 is fixed to the first region 41. An insulating film 55a may be provi