Pressure sensor, audio microphone, blood pressure sensor, and touch panel

• US 9,176,014 B2
• Filed: 06/26/2013
• Issued: 11/03/2015
• Est. Priority Date: 10/03/2012
• Status: Active Grant

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Fuji, Yoshihiko, Fukuzawa, Hideaki, Hara, Michiko, Higashi, Yoshihiro, Hori, Akio, Nagata, Tomohiko, Kaji, Shiori, Yuzawa, Akiko
• Primary Examiner(s): MacChiarolo, Peter
• Assistant Examiner(s): JENKINS, JERMAINE L
• Application Number:
  US13/927,886
• Publication Number:
  US 20140090486A1
• Time in Patent Office: 860 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: G01L 1/12 by measuring variations in the magnetic properties of materials resulting from the application of stress
• CPC Class Codes: G01L 9/0044 Constructional details of non-semiconductive diaphragms
• CPC Class Codes: G01L 9/0048 Details about the mounting of the diaphragm to its support or about the diaphragm edges, e.g. notches, round shapes for stress relief
• CPC Class Codes: G01L 9/16 by making use of variations in the magnetic properties of material resulting from the application of stress
• CPC Class Codes: H04R 1/00 Details of transducers, loudspeakers or microphones
• CPC Class Codes: H04R 15/00 Magnetostrictive transducers magnetostrictive elements in general H10N30/00
• CPC Class Codes: H04R 2410/00 Microphones

Abstract

According to one embodiment, a pressure sensor includes a substrate, a first electrode, a second electrode, a first magnetic layer, a second magnetic, a spacer layer, a third magnetic layer. The substrate includes a first region and a second region. The first electrode is provided on the first region. The second electrode is provided on the first electrode. The first magnetic layer is provided between the first electrode and the second electrode. The second magnetic layer is provided between the first electrode and the first magnetic layer or between the first magnetic layer and the second electrode. The spacer layer is provided between the first magnetic layer and the second magnetic layer in a stacking direction of layers from the first electrode to the second electrode. The third magnetic layer is provided continuously with the second magnetic layer on the second region.

Claims

1. A pressure sensor comprising:

a substrate including a first region and a second region having a thickness thinner than a thickness of the first region;

a first electrode provided on the first region;

a second electrode provided on the first electrode;

a first magnetic layer provided between the first electrode and the second electrode;

a second magnetic layer provided between the first electrode and the first magnetic layer or between the first magnetic layer and the second electrode, a magnetization direction of the second magnetic layer being variable;

a spacer layer provided between the first magnetic layer and the second magnetic layer in a stacking direction of layers from the first electrode to the second electrode; and

a third magnetic layer provided continuously with the second magnetic layer on the second region, a magnetization of the third magnetic layer being changed according to strain caused on the second region.

2. The sensor according to claim 1, wherein the magnetization direction of the second magnetic layer is changed according to a magnetization direction of the third magnetic layer.

3. The sensor according to claim 1, further comprising a fourth magnetic layer provided between the second magnetic layer and the spacer layer, a magnetization direction of the fourth magnetic layer being variable.

4. The sensor according to claim 3, wherein the magnetization direction of the fourth magnetic layer is changed according to a magnetization direction of the second magnetic layer.

5. The sensor according to claim 1, further comprising a fifth magnetic layer provided on the third magnetic layer, a magnetization direction of the fifth magnetic layer being variable.

6. The sensor according to claim 5, wherein the magnetization direction of the fifth magnetic layer is changed according to a magnetization direction of the third magnetic layer.

7. The sensor according to claim 1, wherein an absolute value of a magnetostriction constant of the third magnetic layer is greater than an absolute value of a magnetostriction constant of the second magnetic layer.

8. The sensor according to claim 1, wherein a volume of the third magnetic layer is larger than a volume of the second magnetic layer.

9. The sensor according to claim 1, wherein a projected area of the third magnetic layer to a plane orthogonal to the stacking direction of layers is larger than a projected area of the second magnetic layer to a plane orthogonal to the stacking direction of layers.

10. The sensor according to claim 1, wherein a thickness of the third magnetic layer in the stacking direction of layers is thicker than a thickness of the second magnetic layer in the stacking direction of layers.

11. The sensor according to claim 1, further comprising

a first hard bias provided on the first region, and

a second hard bias provided on the first region,

the second magnetic layer being provided between the first hard bias and the second hard bias in a direction crossing the stacking direction of layers.

12. The sensor according to claim 1, further comprising

a third hard bias provided on the second region, and

a fourth hard bias provided on the second region,

the third magnetic layer being provided between the third hard bias and the fourth hard bias in a direction crossing the stacking direction of layers.

13. The sensor according to claim 1, further comprising

a first hard bias provided on the first region,

a second hard bias provided on the first region,

a third hard bias provided on the second region, and

a fourth hard bias provided on the second region,

the second magnetic layer being provided between the first hard bias and the second hard bias in a direction crossing the stacking direction of layers,

the third magnetic layer being provided between the third hard bias and the fourth hard bias in a direction crossing the stacking direction of layers.

14. The sensor according to claim 13, wherein

the third hard bias is provided continuously with the first hard bias, and

the fourth hard bias is provided continuously with the second hard bias.

15. The sensor according to claim 13, wherein

the third hard bias is provided apart from the first hard bias in a direction crossing the stacking direction of layers, and

the fourth hard bias is provided apart from the second hard bias in a direction crossing the stacking direction of layers.

16. An audio microphone comprising the sensor according to claim 1.

17. A blood pressure sensor comprising the sensor according to claim 1.

18. A touch panel comprising the sensor according to claim 1.

19. A pressure sensor comprising:

a substrate including a first region and a second region having a thickness thinner than a thickness of the first region;

a first electrode provided on the first region;

a second electrode provided on the first electrode;

a first magnetic layer provided between the first electrode and the second electrode;

a second magnetic layer provided between the first electrode and the first magnetic layer or between the first magnetic layer and the second electrode, a magnetization direction of the second magnetic layer being variable;

a spacer layer provided between the first magnetic layer and the second magnetic layer in a stacking direction of layers from the first electrode to the second electrode; and

a third magnetic layer provided on the second region and apart from the second magnetic layer, a magnetization of the third magnetic layer being changed according to strain caused on the second region.

20. The sensor according to claim 19, wherein the magnetization direction of the second magnetic layer is changed according to a magnetization direction of the third magnetic layer.

21. The sensor according to claim 19, wherein an absolute value of a magnetostriction constant of the third magnetic layer is greater than an absolute value of a magnetostriction constant of the second magnetic layer.

22. The sensor according to claim 19, wherein a volume of the third magnetic layer is larger than a volume of the second magnetic layer.

23. The sensor according to claim 19, wherein a projected area of the third magnetic layer to a plane orthogonal to the stacking direction of layers is larger than a projected area of the second magnetic layer to a plane orthogonal to the stacking direction of layers.

24. The sensor according to claim 19, wherein a thickness of the third magnetic layer in the stacking direction of layers is thicker than a thickness of the second magnetic layer in the stacking direction of layers.

25. The sensor according to claim 19, further comprising

a first hard bias provided on the first region, and

a second hard bias provided on the first region,

the second magnetic layer being provided between the first hard bias and the second hard bias in a direction crossing the stacking direction of layers.

26. The sensor according to claim 19, further comprising

a third hard bias provided on the second region, and

a fourth hard bias provided on the second region,

the third magnetic layer being provided between the third hard bias and the fourth hard bias in a direction crossing the stacking direction of layers.

27. The sensor according to claim 19, further comprising

a first hard bias provided on the first region,

a second hard bias provided on the first region,

a third hard bias provided on the second region, and

a fourth hard bias provided on the second region,

the second magnetic layer being provided between the first hard bias and the second hard bias in a direction crossing the stacking direction of layers,

the third magnetic layer being provided between the third hard bias and the fourth hard bias in a direction crossing the stacking direction of layers.

28. The sensor according to claim 27, wherein

the third hard bias is provided continuously with the first hard bias, and

the fourth hard bias is provided continuously with the second hard bias.

29. The sensor according to claim 27, wherein

the third hard bias is provided apart from the first hard bias in a direction crossing the stacking direction of layers, and

the fourth hard bias is provided apart from the second hard bias in a direction crossing the stacking direction of layers.

30. An audio microphone comprising the sensor according to claim 19.

31. A blood pressure sensor comprising the sensor according to claim 19.

32. A touch panel comprising the sensor according to claim 19.