Gas sensor and manufacturing method of the same

Patent metadata

Field	Value
Publication number	US-10598647-B2
Application number	US-201815914828-A
Country	US
Kind code	B2
Filing date	Mar 7, 2018
Priority date	Sep 20, 2017
Publication date	Mar 24, 2020
Grant date	Mar 24, 2020

Abstract

According to one embodiment, a gas sensor is disclosed. The gas sensor includes a substrate region, a first electrode provided on the substrate region, and a movable structure above the first electrode. The movable structure includes a deformable member which deforms by absorbing or adsorbing a predetermined gas, a heat member which heats the deformable member, and a second electrode. The gas sensor further includes a first cavity region which is provided between the first electrode and the second electrode.

First claim

What is claimed is:

1. A gas sensor comprising:
a substrate region;
a first electrode provided on the substrate region;
a movable structure provided above the first electrode and including a deformable member configured to deform by absorbing or adsorbing a predetermined gas, a heating member configured to heat the deformable member, and a second electrode; and
a first cavity region provided between the first electrode and the second electrode.

2. The gas sensor of claim 1 , further comprising a second cavity region provided in the substrate region and connected to the first cavity region,
wherein
the substrate region includes a semiconductor substrate, and a first insulating layer provided on the semiconductor substrate, and
the second cavity region is provided in the first insulating layer.

3. The gas sensor of claim 2 , wherein
a side surface of the first insulating layer defining the second cavity region includes a tapered shape.

4. The gas sensor of claim 2 , further comprising a second insulating layer provided on the first insulating layer, and
wherein a through hole is provided in the second insulating layer, and the first cavity region and the second cavity are connected each other via the through hole.

5. The gas sensor of claim 4 , wherein the first electrode is fixed on the second insulating layer.

6. The gas sensor of claim 4 , wherein a dimension of the second cavity region in a direction from the first electrode toward the movable structure is greater than a dimension of the first cavity region in the direction.

7. The gas sensor of claim 1 , further comprising a second cavity region,
wherein the substrate region includes a semiconductor substrate, and the second cavity region is provided in the semiconductor substrate.

8. The gas sensor of claim 1 , further comprising a second cavity region,
wherein
the movable structure includes at least one movable section and an electrode section, and
the second cavity is provided below the at least one movable section.

9. The gas sensor of claim 8 , wherein
the at least one movable section includes a first movable section and a second movable section, and
the electrode section is provided between the first movable section and the second movable section.

10. The gas sensor of claim 6 , wherein
the at least one movable section each includes a deformable member and a heating member, and
the electrode section includes a second electrode and does not include the deformable member.

11. The gas sensor of claim 1 , further comprising at least one spring section and a second cavity region provided in the substrate region and connected with the first cavity region, and
wherein
the movable structure includes at least one movable section and an electrode section,
the second cavity is provided below the at least one movable section,
each of the at least one movable section is connected to each of the respective at least one spring section, and
each of the at least one spring section has a thermal resistance that is larger than a sum of a thermal resistance of the first cavity region and a thermal resistance of the second cavity region.

12. The gas sensor of claim 11 , wherein
the at least one movable section and the at least one spring section have rotationally symmetric structures when viewed from above.

13. The gas sensor of claim 1 , further comprising at least one spring section each having a straight shape, and a second cavity region provided in the substrate region and connected with the first cavity region, and
wherein
the movable structure includes at least one movable section and an electrode section,
the second cavity is provided below the at least one movable section,
each of the at least one movable section is connected to each of the respective at least one spring section, and
each of the at least one spring section has a thermal resistance that is larger than a sum of a thermal resistance of the first cavity region and a thermal resistance of the second cavity region.

14. The gas sensor of claim 1 , further comprising at least one spring section each having a tensile stress, and a second cavity region provided in the substrate region and connected with the first cavity region, and
wherein
the movable structure includes at least one movable section and an electrode section,
the second cavity is provided below the at least one movable section,
each of the at least one movable section is connected to each of the respective at least one spring section, and
each of the at least one spring section has a thermal resistance that is larger than a sum of a thermal resistance of the first cavity region and a thermal resistance of the second cavity region.

15. The gas sensor of claim 1 , wherein the predetermined gas contains hydrogen.

16. The gas sensor of claim 15 , wherein the deformable member contains palladium, an alloy containing palladium, an alloy containing palladium in which supper and silicon are contained, an alloy containing titanium, an alloy containing lanthanum, or metallic glass.

17. The gas sensor of claim 1 , wherein the movable structure is configured to move in such a manner that a distance between the first electrode and the second electrode changes accordance to a deformation of the deformable member.

18. A manufacturing method of a gas sensor, comprising:
forming a first insulating layer, a second insulating layer, and a first electrode in sequence on a semiconductor substrate;
forming a third insulating layer on the second insulating layer and the first electrode;
forming a through hole penetrating the third insulating layer and the second insulating layer and reaching the first insulating layer;
forming a fourth insulating layer on the first insulating layer and the third insulating layer to fill the through hole with the fourth insulating layer;
forming a movable structure on the fourth insulating layer, the movable structure including a deformable member configured to deform by absorbing or adsorbing a predetermined gas, a heating member configured to heat the deformable member, and a second electrode; and
forming a first cavity region between the first electrode and the second electrode, by removing the fourth insulating layer.

19. The manufacturing method of the gas sensor of claim 18 , wherein
each of the first and fourth insulating layers contains a first material, and each of second and third insulating layers contain a second material different in type from the first material.

20. The manufacturing method of the gas sensor of claim 19 , further comprising forming a second cavity region connected to the first cavity region, by removing a part of the first insulating layer,
wherein forming of the first and second cavity region includes etching the first and fourth insulating layers on a condition that etching rates of the first and fourth insulating layers are greater than etching rates of the second and third insulating layers.

Assignees

• Toshiba Kk

Inventors

• Ikehashi Tamio
• Yamazaki Hiroaki

Classifications

• G01N27/227

  Sensors changing capacitance upon adsorption or absorption of fluid components, e.g. electrolyte-insulator-semiconductor sensors, MOS capacitors (G01N27/225 takes precedence) · CPC title

• G01N27/226 Primary

  Construction of measuring vessels; Electrodes therefor · CPC title

• G01N33/0022 Primary

  using a number of analysing channels · CPC title

• G01N25/20

  by investigating the development of heat, i.e. calorimetry, e.g. by measuring specific heat, by measuring thermal conductivity (calorimeters per se G01K) · CPC title

• G01N27/221

  by investigating the dielectric properties (using microwaves G01N22/00; measuring loss factors or dielectric constants per se G01R27/26) · CPC title