Pressure sensor, acceleration sensor, and method for manufacturing pressure sensor

Patent metadata

Field	Value
Publication number	US-9322726-B2
Application number	US-201414565755-A
Country	US
Kind code	B2
Filing date	Dec 10, 2014
Priority date	Jan 20, 2014
Publication date	Apr 26, 2016
Grant date	Apr 26, 2016

Abstract

According to one embodiment, a pressure sensor includes a base and a sensor unit provided on the base. The sensor unit includes a transducing thin film having a first surface, a first strain sensing element provided on the first surface, and a second strain sensing element provided on the first surface. The first strain sensing element includes a first magnetic layer, a first film having a first oxygen concentration, a second magnetic layer provided between the first magnetic layer and the first film, and a first intermediate layer provided between the first and the second magnetic layer. The second strain sensing element includes a third magnetic layer, a second film having a second oxygen concentration different from the first concentration, a fourth magnetic layer provided between the third magnetic layer and the second film, and a second intermediate layer provided between the third and the fourth magnetic layer.

First claim

What is claimed is:

1. A pressure sensor, comprising:
a base; and
a sensor unit provided on the base,
the sensor unit including:
a transducing thin film having a first surface and being flexible;
a first strain sensing element provided on the first surface; and
a second strain sensing element provided on the first surface and separated from the first strain sensing element,

the first strain sensing element including:
a first magnetic layer having a first magnetization being changeable;
a first film including oxygen at a first oxygen concentration;
a second magnetic layer provided between the first magnetic layer and the first film, the second magnetic layer having a second magnetization being fixed; and
a first intermediate layer provided between the first magnetic layer and the second magnetic layer,

the second strain sensing element including:
a third magnetic layer having a third magnetization being changeable;
a second film having a second oxygen concentration different from the first oxygen concentration;
a fourth magnetic layer provided between the third magnetic layer and the second film, the fourth magnetic layer having a fourth magnetization being fixed direction; and
a second intermediate layer provided between the third magnetic layer and the fourth magnetic layer.

2. The sensor according to claim 1 , wherein
the first film includes a first metallic element having a first valence, and
the second film includes the first metallic element having a second valence different from the first valence.

3. The sensor according to claim 1 , wherein
the first oxygen concentration of the first film is not less than 20 atomic percent and not more than 70 atomic percent, and
the second oxygen concentration of the second film is not less than 0 atomic percent and not more than 20 atomic percent.

4. The sensor according to claim 1 , wherein the first film includes at least one selected from iron, chrome, nickel, and manganese.

5. The sensor according to claim 1 , wherein
the first strain sensing element further includes a first ferromagnetic layer,
the first film is provided between the second magnetic layer and the first ferromagnetic layer,
the second strain sensing element further includes a second ferromagnetic layer, and
the second film is provided between the fourth magnetic layer and the second ferromagnetic layer.

6. The sensor according to claim 5 , wherein
the first strain sensing element further includes a first antiferromagnetic layer,
the first ferromagnetic layer is provided between the second magnetic layer and the first antiferromagnetic layer,
the second strain sensing element further includes a second antiferromagnetic layer, and
the second ferromagnetic layer is provided between the fourth magnetic layer and the second antiferromagnetic layer.

7. The sensor according to claim 1 , wherein a direction from a centroid of the transducing thin film toward the first strain sensing element intersects a direction from the centroid toward the second strain sensing element.

8. The sensor according to claim 1 , wherein a distance between the first strain sensing element and a centroid of the transducing thin film is not less than 0.8 times and not more than 1.2 times a distance between the centroid and the second strain sensing element.

9. The sensor according to claim 1 , wherein
the sensor unit further includes a fixing unit, and
the fixing unit is connected to an edge portion of the transducing thin film and fixes the edge portion to the base.

10. The sensor according to claim 1 , wherein a length of the first strain sensing element along a first direction from a centroid of the transducing thin film toward the first strain sensing element is different from a length of the first strain sensing element along a second direction perpendicular to the first direction.

11. The sensor according to claim 1 , wherein at least one selected from the first magnetic layer and the second magnetic layer includes at least one selected from iron, cobalt, and nickel.

12. The sensor according to claim 1 , wherein the first intermediate layer includes at least one selected from magnesium oxide, aluminum oxide, titanium oxide, and zinc oxide.

13. An acceleration sensor, comprising:
a base unit;
a plummet;
a connector connecting the plummet and the base unit, the connector being deformable according to a change of a position of the plummet relative to the base unit;
a first strain sensing element provided on a first portion of the connector; and
a second strain sensing element provided on a second portion of the connector, the second portion being separated from the first portion,
the first strain sensing element including:
a first magnetic layer having a first magnetization being changeable;
a first film including oxygen at a first oxygen concentration;
a second magnetic layer provided between the first magnetic layer and the first film, the second magnetic layer having a second magnetization being fixed; and
a first intermediate layer provided between the first magnetic layer and the second magnetic layer,

the second strain sensing element including:
a third magnetic layer having a third magnetization being changeable;
a second film having a second oxygen concentration different from the first oxygen concentration;
a fourth magnetic layer provided between the third magnetic layer and the second film, the fourth magnetic layer having a fourth magnetization being fixed; and
a second intermediate layer provided between the third magnetic layer and the fourth magnetic layer.

14. A method for manufacturing a pressure sensor, the pressure sensor including a base and a sensor unit provided on the base, the sensor unit including a transducing thin film, a first strain sensing element, and a second strain sensing element, the transducing thin film having a first surface and being flexible, the first strain sensing element being provided on the first surface, the second strain sensing element being provided on the first surface and separated from the first strain sensing element, the first strain sensing element including a first magnetic layer, a first film, a second magnetic layer, and a first intermediate layer, the first magnetic layer having a first magnetization being changeable, the second magnetic layer being provided between the first magnetic layer and the first film and having a second magnetization being fixed, the first intermediate layer being provided between the first magnetic layer and the second magnetic layer, the second strain sensing element including a third magnetic layer, a second film, a fourth magnetic layer, and a second intermediate layer, the third magnetic layer having a third magnetization being changeable, the fourth magnetic layer being provided between the third magnetic layer and the second film and having a fourth magnetization being fixed, the second intermediate layer being provided between the third magnetic layer and the fourth magnetic layer, the method comprising:
forming a first oxide film used to form the first film.

15. The method according to claim 14 , wherein the first film includes at least one selected from iron, chrome, nickel, and manganese.

16. The method according to claim 14 , further comprising forming a second oxide film used to form the second film,
an oxidation amount of the forming of the first oxide film being different from an oxidation amount of the forming of the second oxide film.

17. The method according to claim 14 , wherein
the first strain sensing element fu

Assignees

• Toshiba Kk

Inventors

• Fukuzawa Hideaki
• Fuji Yoshihiko
• Higashi Yoshihiro
• Hara Michiko

Classifications

• G01L9/16

  by making use of variations in the magnetic properties of material resulting from the application of stress · CPC title

• G01L1/12

  by measuring variations in the magnetic properties of materials resulting from the application of stress · CPC title

• G01L1/125

  by using magnetostrictive means (magnetostrictive sensors H10N35/101) · CPC title

• G01P15/105

  by magnetically sensitive devices · CPC title

• G01L1/2287 Primary

  constructional details of the strain gauges (adjustable resistors H01C10/00) · CPC title