Sensor And Method For Producing A Sensor

• US 20070186666A1
• Filed: 01/05/2007
• Published: 08/16/2007
• Est. Priority Date: 07/05/2004
• Status: Active Grant

• Current Assignee: Infineon Technologies AG
• Original Assignee: Infineon Technologies AG
• Inventors: Ruehrig, Manfred, Zimmer, Juergen, Schmitt, Stephan
• Granted Patent: US 7,490,522 B2
• Time in Patent Office: Days
• US Class Current: 73/779
• 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 9/16 by making use of variations in the magnetic properties of material resulting from the application of stress

Abstract

A sensor has a substrate in which a mechanically deformable area is formed. A first magnetostrictive multilayer sensor element and a second magnetostrictive multilayer sensor element are formed in the mechanically deformable area, wherein the first magnetostrictive multilayer sensor element and the second magnetostrictive multilayer sensor element are connected to each other and implemented such that when generating a mechanical deformation of the mechanically deformable area, the electric resistance of the first magnetostrictive multilayer sensor element changes in an opposite way to the electric resistance of the second magnetostrictive multilayer sensor element, or the electric resistance of the first magnetostrictive multilayer sensor element remains unchanged.

Claims

1. A sensor, comprising:

a substrate;

a mechanically deformable area formed in the substrate; and

a first magnetostrictive multilayer sensor element and a second magnetostrictive multilayer sensor element, each arranged at least partly in the mechanically deformable area, wherein the first magnetostrictive multilayer sensor element and the second magnetostrictive multilayer sensor element are connected to each other and implemented such that when generating a mechanical deformation of the mechanically deformable area, the electric resistance of the first magnetostrictive multilayer sensor element changes in opposition to the electric resistance of the second magnetostrictive multilayer sensor element, or the electric resistance of the first magnetostrictive multilayer sensor element remains unchanged, wherein the first and second magnetostrictive multilayer sensor elements are spin-valve sensor elements and a magnetization of the magnetically hard layer of the first sensor element and the second sensor element have the same direction.

2. The sensor according to claim 1, wherein a magnetization of the magnetically soft layer of the first sensor element and the second sensor element point to the same direction without mechanical deformation of the mechanically deformable area.

3. The sensor element according claim 1, wherein the magnetization of the magnetically soft layer without mechanical deformation of the mechanically deformable area and an expansion direction, which would each result at the location of the first and second sensor elements when a force is applied to the mechanically deformable area, each have an angle of 45°

, 90°

or 135°

for the first and second sensor elements.

4. The sensor element according to claim 1, wherein an angle between the magnetization of the magnetically soft layer of the first sensor element without mechanical deformation of the mechanically deformable area and an expansion direction, which would result at the location of the first sensor element when a force is applied to the mechanically deformable area, has a value of 0°

or 180°

.

5. The sensor element according to claim 1, wherein, without mechanical deformation of the mechanically deformable area, the magnetization of the magnetically hard layer and the magnetization of the magnetically soft layer of each of the first sensor element and the second sensor element are adjusted such that they have an angle of 45°

, 90°

or 135°

.

6. The sensor element according to claim 1, wherein the magnetization of the magnetically hard layer and an expansion direction, which would result at the location of the first and second sensor elements when a force is applied to the mechanically deformable area, each have an angle of 0°

, 45°

, 90°

, 135°

or 180°

for the first and second sensor elements.

7. The sensor according to claim 1, wherein the first sensor element and the second sensor element have a positive magnetostriction coefficient.

8. The sensor according to claim 1, wherein the first sensor element and the second sensor element have a negative magnetostriction coefficient.

9. The sensor according to claim 1, wherein the mechanically deformable area has a symmetry point, wherein the first sensor element and the second sensor element have the same distance from the symmetry point.

10. The sensor according to claim 1, wherein the mechanically deformable area is implemented in a square or round way, wherein the first sensor element is arranged along a first portion of the mechanically deformable area, and the second sensor element is arranged along a portion adjacent to the portion of the mechanically deformable area.

11. The sensor according to claim 1, wherein the first sensor element and the second sensor element are sensor elements of a branch of a bridge circuit.

12. The sensor according to claim 11, wherein a third sensor element, which corresponds to the first sensor element, and a fourth sensor element, which corresponds to the second sensor element, are connected to each other in a further branch of the bridge.

13. The sensor according to claim 11, wherein the resistances of the sensor elements change differently within a bridge branch under mechanical stress.

14. The sensor according to claim 1, wherein a further sensor element is located at a location in the mechanically deformable area, which has a deformation when a force is applied to the mechanically deformable area, which differs from a deformation at the location of the first sensor element or the second sensor element.

15. The sensor according to claim 14, wherein the mechanically deformable area has a symmetry point, wherein the further sensor element has a first distance to the symmetry point, while the first and second sensor elements each have a distance to the symmetry point differing from the first distance.

16. The sensor according to claim 14, wherein a plurality of further sensor elements are arranged in the mechanically deformable area, wherein the plurality of further sensor elements are arranged at locations, which have a deformation, when pressure is applied to the mechanically deformable area, which differs from a deformation at the location of the first sensor element and the second sensor element.

17. The sensor according to claim 16, wherein the plurality of further sensor elements are connected to a bridge.

18. A method for producing a sensor, comprising:

generating a mechanically deformable area in a substrate;

generating a first magnetostrictive multilayer sensor element and a second magnetostrictive multilayer sensor element, each at least partly in the mechanically deformable area, wherein the same are implemented such that when generating a mechanical deformation of the of the mechanically deformable area, the electric resistance of the first magnetostrictive multilayer sensor element changes in opposition to the electric resistance of the second magnetostrictive multilayer sensor element, or the electric resistance of the first magnetostrictive multilayer sensor element remains unchanged, wherein the first and second magnetostrictive multilayer sensor elements are spin-valve sensor elements and a magnetization of the magnetically hard layer of the first sensor element and the second sensor element have the same direction; and

connecting the first magnetostrictive multilayer sensor element and the second magnetostrictive multilayer sensor element.

19. The method according to claim 18, wherein the step of generating first and second magnetostrictive sensor elements comprises generating first and second spin-valve sensor elements.

20. The method according to claim 19, wherein the step of generating the first and second sensor elements comprises aligning the magnetization of the magnetically hard layer of the first sensor element and the second sensor element in the same direction.

21. The method according to claim 19, wherein the step of generating the first and second sensor elements comprises aligning, so that the magnetization of the magnetically soft layer without mechanical deformation of the mechanical deformable area and an expansion direction, which would each result at the location of the first and second sensor elements when a force is applied to the mechanically deformable area, each have an angle of 45°

, 90°

or 135°

for the first and second sensor elements.

22. The method according to claim 19, wherein the step of generating the first and second sensor elements comprises aligning, so that an angle between the magnetization of the magnetically soft layer of the first sensor element without mechanical deformation of the mechanically deformable area and an expansion direction, which would result at the location of the first sensor element when a force is applied to the mechanically deformable area, has a value of 0°

or 180°

.

23. The method according to claim 19, wherein the step of generating the first and second sensor element comprises aligning, so that without mechanical deformation of the mechanically deformable area, the magnetization (of the magnetically hard layer and the magnetization of the magnetically soft layer of each of the first sensor element and the second sensor element are adjusted such that they have an angle of 45°

, 90°

or 135°

.

24. The method according to claim 18, wherein the magnetization of the magnetically hard layer and an expansion direction, which would result at the location of the first and second sensor elements when a force is applied to the mechanically deformable area, each have an angle of 0°

, 45°

, 90°

, 135°

or 180°

for the first and second sensor elements.