Magnetoresistive Magnetic Field Sensor Structure

• US 20090015252A1
• Filed: 07/10/2008
• Published: 01/15/2009
• Est. Priority Date: 07/13/2007
• Status: Active Grant

• Current Assignee: Infineon Technologies AG
• Original Assignee: Infineon Technologies AG
• Inventors: Zimmer, Juergen, Raberg, Wolfgang
• Granted Patent: US 8,063,633 B2
• Time in Patent Office: Days
• US Class Current: 324/252
• CPC Class Codes: B82Y 25/00 Nanomagnetism, e.g. magnetoimpedance, anisotropic magnetoresistance, giant magnetoresistance or tunneling magnetoresistance
• CPC Class Codes: G01R 33/093 using multilayer structures, e.g. giant magnetoresistance sensors thin magnetic films H01F10/00
• CPC Class Codes: H10B 61/00 Magnetic memory devices, e.g. magnetoresistive RAM [MRAM] devices
• CPC Class Codes: H10N 59/00 Integrated devices, or assemblies of multiple devices, comprising at least one galvanomagnetic or Hall-effect element covered by groups H10N50/00 - H10N52/00 MRAM devices H10B61/00
• CPC Class Codes: Y10T 29/4902 Electromagnet, transformer or inductor

Abstract

A magnetic field sensor structure including a first magnetoresistive element in a spin-valve arrangement with a first reference layer structure with a first reference magnetization direction and a second magnetoresistive element in a spin-valve arrangement with a second reference layer structure with a second reference magnetization direction, wherein the first and second magnetoresistive elements are arranged in a layer vertically above each other and galvanically isolated from each other by an intermediate layer, and wherein the first and second reference magnetization directions are different.

Claims

1. A magnetic field sensor structure comprising

a first magnetoresistive element in a spin-valve arrangement with a first reference layer structure with a first reference magnetization direction;

and

a second magnetoresistive element in a spin-valve arrangement with a second reference layer structure with a second reference magnetization direction,

wherein the first and second magnetoresistive elements are arranged in a layer stack vertically above each other and galvanically isolated from each other by an intermediate layer, and wherein the first and second reference magnetization directions are different.

2. The magnetic field sensor structure as claimed in claim 1, wherein the first and second reference magnetization directions are opposed to each other.

3. The magnetic field sensor structure as claimed in claim 1, wherein the first magnetoresistive element comprises a first ferromagnetic layer structure antiferromagnetically coupled to the first reference layer structure.

4. The magnetic field sensor structure as claimed in claim 3, wherein a first layer thickness ratio D_PL,1/D_RL,1 of a thickness D_PL,1 of the first ferromagnetic layer structure to a thickness D_RL,1 of the first reference layer structure is greater than 1.

5. The magnetic field sensor structure as claimed in claim 3, wherein the second magnetoresistive element comprises a second ferromagnetic layer structure antiferromagnetically coupled to the second reference layer structure.

6. The magnetic field sensor structure as claimed in claim 5, wherein a second layer thickness ratio D_PL,2/D_RL,2 of a thickness D_PL,2 of the second ferromagnetic layer structure to a thickness D_RL,2 of the second reference layer structure is smaller than 1.

7. The magnetic field sensor structure as claimed in claim 6, wherein the first layer thickness ratio D_PL,1/D_RL,1 is inverse to the second layer thickness ratio D_PL,2/D_RL,2.

8. The magnetic field sensor structure as claimed in claim 3, wherein a layer thickness D_RL,1 of the first reference layer structure deviates by no more than 75% of the layer thickness of the first reference layer structure from a layer thickness D_PL,1 of the first ferromagnetic layer structure.

9. The magnetic field sensor structure as claimed in claim 3, wherein a layer thickness D_RL,2 of the second reference layer structure deviates by no more than 75% of the layer thickness of the second reference layer structure from a layer thickness D_PL,2 of the second ferromagnetic layer structure.

10. The magnetic field sensor structure as claimed in claim 1, wherein the first magnetoresistive element comprises an odd number of ferromagnetic layer structures antiferromagnetically coupled to one another, and wherein the second magnetoresistive element comprises an even number of ferromagnetic layer structures antiferromagnetically coupled to one another.

11. The magnetic field sensor structure as claimed in claim 10, wherein the first reference layer structure is a topmost or bottommost ferromagnetic layer structure of a layer structure stack of the odd-numbered layer structures antiferromagnetically coupled to one another, and wherein the second reference layer structure is a topmost or bottommost ferromagnetic layer structure of a layer structure stack of the even-numbered layer structures antiferromagnetically coupled to one another.

12. The magnetic field sensor structure as claimed in claim 1, wherein the first and/or the second magnetoresistive element(s) is/are implemented as a GMR spin-valve element (GMR=giant magnetoresistance).

13. The magnetic field sensor structure as claimed in claim 1, wherein the first and/or the second magnetoresistive element(s) is/are implemented as a TMR spin-valve element (TMR=tunneling magnetoresistance).

14. A magnetic field detection device comprising

a first magnetoresistive element in a spin-valve arrangement with a first reference layer structure with a first reference magnetization direction;

and

a second magnetoresistive element in a spin-valve arrangement with a second reference layer structure with a second reference magnetization direction,

wherein the first and second magnetoresistive elements are arranged in a layer stack vertically above each other and galvanically isolated from each other by an intermediate layer, and wherein the first and second reference magnetization directions are opposed to each other; and

wherein the first and second magnetoresistive elements are connected in a bridge circuit such that, due to an inverse change in resistance values of the first and second magnetoresistive elements, a difference signal is detectable proportionally to a magnetic field and/or a magnetic field change between two bridge arms of the bridge circuit.

15. The magnetic field detection device as claimed in claim 14, wherein the first and second reference magnetization directions are anti-parallel, and wherein the changes in the resistance values of the first and second magnetoresistive elements thus are opposed to each other.

16. The magnetic field detection device as claimed in claim 14, wherein the first magnetoresistive element comprises a first ferromagnetic layer structure antiferromagnetically coupled to the first reference layer structure.

17. The magnetic field detection device as claimed in claim 16, wherein a first layer thickness ratio D_PL,1/D_RL,1 of a thickness D_PL,1 of the first ferromagnetic layer structure to a thickness D_RL,1 of the first reference layer structure is greater than 1.

18. The magnetic field detection device as claimed in claim 16, wherein the second magnetoresistive element comprises a second ferromagnetic layer structure antiferromagnetically coupled to the second reference layer structure.

19. The magnetic field detection device as claimed in claim 18, wherein a second layer thickness ratio D_PL,2/D_RL,2 of a thickness D_PL,2 of the second ferromagnetic layer structure to a thickness D_RL,2 of the second reference layer structure is smaller than 1.

20. The magnetic field detection device as claimed in claim 19, wherein the first layer thickness ratio D_PL,1/D_RL,1 is inverse to the second layer thickness ratio D_PL,2/D_RL,2.

21. The magnetic field detection device as claimed in claim 16, wherein a layer thickness D_RL,1 of the first reference layer structure deviates by no more than 75% of the layer thickness of the first reference layer structure from a layer thickness D_PL,1 of the first ferromagnetic layer structure.

22. The magnetic field detection device as claimed in claim 16, wherein a layer thickness D_RL,2 of the second reference layer structure deviates by no more than 75% of the layer thickness of the second reference layer structure from a layer thickness D_PL,2 of the second ferromagnetic layer structure.

23. The magnetic field detection device as claimed in claim 14, wherein the first magnetoresistive element comprises an odd number of ferromagnetic layer structures antiferromagnetically coupled to one another, and wherein the second magnetoresistive element comprises an even number of ferromagnetic layer structures antiferromagnetically coupled to one another.

24. The magnetic field detection device as claimed in claim 14, further comprising

a third magnetoresistive element in a spin-valve arrangement with a third reference layer structure with a third reference magnetization direction;

and

a fourth magnetoresistive element in a spin-valve arrangement with a fourth reference layer structure with a fourth reference magnetization direction,

wherein the third and fourth magnetoresistive elements are arranged in a layer stack vertically above each other and galvanically isolated from each other by an intermediate layer structure, and wherein the third and fourth reference magnetization directions are opposed to each other; and

wherein the first, second, third and fourth magnetoresistive elements are connected in a bridge circuit such that, due to an inverse change in resistance values of the first and second magnetoresistive elements and of the third and fourth magnetoresistive elements, a difference signal is detectable proportionally to the magnetic field and/or a magnetic field change between two bridge arms of the bridge circuit.

25. A method of measuring a magnetic field and/or a magnetic field change, the method comprising:

arranging a layer stack of a first magnetoresistive element in a spin-valve arrangement with a first reference layer structure with a first reference magnetization direction and a second magnetoresistive element, galvanically isolated from the first magnetoresistive element, in a spin-valve arrangement with a second reference layer structure with a second reference magnetization direction, the first and second reference magnetization directions being different;

detecting a signal based on a first resistance change in the first magnetoresistive element and a second resistance change in the second magnetoresistive element which is inverse to the first resistance change on account of the magnetic field and/or the magnetic field change, the magnetic field and/or the magnetic field change being assignable to the signal detected.

26. The method as claimed in claim 25, wherein arranging comprises connecting the first and second magnetoresistive elements in a bridge circuit, so that, because of the inverse change in the resistance values, a signal is detectable proportionally to the magnetic field and/or the magnetic field change between two bridge arms of the bridge circuit.

27. The method as claimed in claim 25, further comprising:

arranging a third magnetoresistive element in a spin-valve arrangement with a third reference layer structure with a third reference magnetization direction, and a fourth magnetoresistive element in a spin-valve arrangement with a fourth reference layer structure with a fourth reference magnetization direction, wherein the third and fourth magnetoresistive elements are arranged in a layer stack vertically above each other and galvanically isolated from each other by an intermediate layer, and wherein the third and fourth reference magnetization directions are opposed to each other; and

connecting the first, second, third and fourth magnetoresistive elements in a bridge circuit in such a manner that, due to an inverse change in resistance values of the first and second magnetoresistive elements and of the third and fourth magnetoresistive elements, a difference signal is detectable proportionally to the magnetic field and/or a magnetic field change between two bridge arms of the bridge circuit.

28. The method as claimed in claim 25, further comprising:

arranging a back-bias magnet for providing a bias magnetic field.

29. A method of producing a magnetic field sensor structure, the method comprising:

arranging a first magnetoresistive element in a spin-valve arrangement with a first reference layer structure with a layer thickness D_RL,1 and a first ferromagnetic layer structure with a layer thickness D_PL,1;

arranging a second magnetoresistive element, vertically above the first magnetoresistive element and galvanically isolated therefrom, in a spin-valve arrangement with a second reference layer structure with a layer thickness D_RL,2 and a second ferromagnetic layer structure with a layer thickness D_PL,2, wherein a first layer thickness ratio of the layer thickness D_PL,1 to the layer thickness D_RL,1 is greater than 1, and a layer thickness ratio of the layer thickness D_PL,2 to the layer thickness D_RL,2 is smaller than 1; and

exposing the first magnetoresistive element and the second magnetoresistive element to a magnetization field with an advantageous magnetization direction during a magnetization write-in process in order to achieve different reference magnetization directions in the first and second reference layer structures.

30. The method as claimed in claim 29, wherein exposing comprises achieving opposed reference magnetization directions in the first and second reference layer structures.

31. The method as claimed in claim 29, further comprising:

adjusting the field strength of the magnetization field to a value of between 5 and 250 mT.

32. The method as claimed in claim 29, wherein the first and second magnetoresistive elements are arranged such that the first layer thickness ratio D_PL,1/D_RL,1 is inverse to the second layer thickness ratio D_PL,2/D_RL,2.

33. The method as claimed in claim 29, wherein the first magnetoresistive element is arranged such that the layer thickness D_RL,1 of the first reference layer structure deviates by no more than 75% of the layer thickness of the first reference layer structure from a layer thickness D_PL,1 of the first ferromagnetic layer structure.

34. The method as claimed in claim 29, wherein the second magnetoresistive element is arranged such that the layer thickness D_RL,2 of the second reference layer structure deviates by no more than 75% of the layer thickness of the second reference layer structure from a layer thickness D_PL,2 of the second ferromagnetic layer structure.

35. The method as claimed in claim 29, wherein the first and/or the second magnetoresistive element(s) is/are implemented as GMR spin-valve elements (GMR=giant magnetoresistance).

36. The method as claimed in claim 29, wherein the first and/or the second magnetoresistive element(s) is/are implemented as TMR spin-valve elements (TMR=tunneling magnetoresistance).

37. The method as claimed in claim 29, wherein the magnetic field sensor structure is manufactured as an integrated component in a CMOS semiconductor processing method.

38. A method of producing a magnetic field sensor structure, the method comprising:

arranging a first magnetoresistive element in a spin-valve arrangement with a first reference layer structure with a layer thickness D_RL,1 and a first ferromagnetic layer structure with a layer thickness D_PL,1;

arranging a second magnetoresistive element, vertically above the first magnetoresistive element and galvanically isolated therefrom, in a spin-valve arrangement with a second reference layer structure;

wherein a first layer thickness ratio of the layer thickness D_PL,1 to the layer thickness D_RL,1 is greater than 1; and

exposing the first magnetoresistive element and the second magnetoresistive element to a magnetization field with an advantageous magnetization direction during a magnetization write-in process in order to achieve different reference magnetization directions in the first and second reference layer structures.

39. The method as claimed in claim 38, wherein exposing comprises achieving opposed reference magnetization directions in the first and second reference layer structures.

40. The method as claimed in claim 38, further comprising:

adjusting the field strength of the magnetization field to a minimum value of 5 mT.

41. The method as claimed in claim 38, wherein the first magnetoresistive element is arranged such that the layer thickness D_RL,1 of the first reference layer structure deviates by no more than 75% of the layer thickness of the first reference layer structure from a layer thickness D_PL,1 of the first ferromagnetic layer structure.

42. The method as claimed in claim 38, wherein the magnetic field sensor structure is manufactured as an integrated component in a CMOS semiconductor processing method.

43. A method of producing a magnetic field sensor structure, the method comprising:

arranging a first magnetoresistive element in a spin-valve arrangement with an odd number of ferromagnetic layer structures which may be antiferromagnetically coupled to one other;

arranging a second magnetoresistive element, vertically above the first magnetoresistive element and galvanically isolated therefrom, in a spin-valve arrangement with an even number of ferromagnetic layer structures which may be antiferromagnetically coupled to one other; and

exposing the first magnetoresistive element and the second magnetoresistive element to a magnetization field with an advantageous magnetization direction during a magnetization write-in process in order to achieve a first ferromagnetic reference layer structure of the first magnetoresistive element and a second ferromagnetic reference layer structure of the second magnetoresistive element, which comprise different reference magnetization directions.

44. The method as claimed in claim 43, wherein exposing comprises achieving opposed reference magnetization directions in the first and second reference layer structures.

45. The method as claimed in claim 43, wherein exposing comprises antiferromagnetically coupling the ferromagnetic layer structures of the first magnetoresistive element and of the second magnetoresistive element to one another in each case.

46. The method as claimed in claim 43, wherein exposing comprises forming the first reference layer structure from a topmost or bottommost ferromagnetic layer structure of a layer structure stack of the odd-numbered layer structures antiferromagnetically coupled to one another, and wherein the second reference layer structure is formed from a topmost or bottommost ferromagnetic layer structure of a layer structure stack of the even-numbered layer structures antiferromagnetically coupled to one another.

47. The method as claimed in claim 43, further comprising:

adjusting the field strength of the magnetization field to a minimum value of 500 mT.