Magnetic film sensor and method of manufacturing the same

• US 20080094059A1
• Filed: 10/24/2006
• Published: 04/24/2008
• Est. Priority Date: 10/24/2006
• Status: Active Grant

• Current Assignee: Headway Technologies Incorporated (TDK Corporation), SAE Magnetics Limited (TDK Corporation)
• Original Assignee: Koji Shimazawa, Headway Technologies Incorporated (TDK Corporation), SAE Magnetics (HK) Limited (TDK Corporation)
• Inventors: Shimazawa, Koji, Sasaki, Yoshitaka, Shimizu, Tatsushi
• Granted Patent: US 7,750,627 B2
• Time in Patent Office: Days
• US Class Current: 324/252
• CPC Class Codes: G01R 33/18 Measuring magnetostrictive properties
• CPC Class Codes: Y10T 29/4902 Electromagnet, transformer or inductor

Abstract

A magnetic film sensor comprises a magnetic film for generating a magnetostriction, and a magnetostrictive structure for generating a magnetostriction in the magnetic film. The magnetostrictive structure is constructed so as to generate a magnetostriction by curving the magnetic film, for example. The magnetostrictive structure is obtained, for example, by providing a depressed insulating layer having a surface formed with a depression and forming the magnetic film across the depression.

Claims

1. A magnetic film sensor comprising a spin-valve film for generating a magnetostriction, and a magnetostrictive structure for generating a magnetostriction in the spin-valve film.

2. A magnetic film sensor according to claim 1, wherein the magnetostrictive structure is constructed so as to generate the magnetostriction by curving the spin-valve film.

3. A magnetic film sensor according to claim 1, wherein the spin-valve film is constructed so as to change a resistance value according to the magnetostriction.

4. A magnetic film sensor comprising a magnetic film for generating a magnetostriction and a depressed insulating layer having a surface formed with a depression, the magnetic film being formed on the depressed insulating layer so as to stride across the depression.

6. A magnetic film sensor according to claim 4, further comprising a buffer insulating layer formed on the surface of the depressed insulating layer so as to stride across the depression, the magnetic film being formed on the buffer insulating layer.

8. A magnetic film sensor according to claim 4, further comprising first and second permanent magnet layers for applying a magnetic field along a direction across the depression, the first and second permanent magnet layers being arranged on respective sides of the magnetic film in the direction across the depression.

10. A magnetic film sensor according to claim 4, further comprising first and second electrodes for energizing the magnetic film, the first and second electrodes being arranged on respective sides of the magnetic film in the direction across the depression.

12. A magnetic film sensor according to claim 4, wherein a track width of the magnetic film in the direction across the depression is formed greater than a length in a direction intersecting the track width.

13. A magnetic film sensor according to claim 4, wherein the magnetic film has a structure in which an insulating layer is held between one of GMR, AMR, MR, TMR, and CPP films and a permanent magnet layer made of a permanent magnet.

14. A magnetic film sensor according to claim 4, wherein the magnetic film has a structure in which a free magnetization layer whose orientation of magnetization varies according to a change in the track width in the direction across the depression, and a fixed magnetization layer whose orientation of magnetization is unchangeable are laminated.

15. A magnetic film sensor according to claim 4, further comprising first and second permanent magnet layers for applying a magnetic field to the magnetic film along the direction across the depression,

the magnetic film having a structure in which an insulating layer is held between a GMR film and a bias magnetic field layer for applying a magnetic field in a direction intersecting the magnetic field applied by the first and second permanent magnet layers to the GMR film.

17. A magnetic film sensor according to claim 8, further comprising a third permanent magnet layer for connecting the first and second permanent magnet layers to each other, and a thin-film coil wound about one of the first, second, and third permanent magnet layers.

18. A magnetic film sensor according to claim 4, further comprising a bimetal formed on the surface of the depressed insulating layer so as to stride across the depression, the magnetic film being formed on the bimetal.

19. A magnetic film sensor according to claim 4 having a structure in which a photoresist is buried in the depression.

5. A magnetic film sensor comprising a magnetic film for generating a magnetostriction and a base layer having a surface at least partly forming a deformable part softer than the magnetic film, the magnetic film being formed on the base layer so as to stride across the deformable part.

7. A magnetic film sensor according to claim 5, further comprising a buffer insulating layer formed on the surface of the base layer so as to stride across the deformable part, the magnetic film being formed on the buffer insulating layer.

9. A magnetic film sensor according to claim 5, further comprising first and second permanent magnet layers for applying a magnetic field along a direction across the deformable part, the first and second permanent magnet layers being arranged on respective sides of the magnetic film in the direction across the deformable part.

11. A magnetic film sensor according to claim 5, further comprising first and second electrodes for energizing the magnetic film, the first and second electrodes being arranged on respective sides of the magnetic film in the direction across the deformable part.

16. A magnetic film sensor according to claim 5, further comprising first and second permanent magnet layers for applying a magnetic field to the magnetic film along the direction across the deformable part,

the magnetic film having a structure in which an insulating layer is held between a GMR film and a bias magnetic field layer for applying a magnetic field in a direction intersecting the magnetic field applied by the first and second permanent magnet layers to the GMR film.

20. A method of manufacturing a magnetic film sensor comprising a magnetic film for generating a magnetostriction and a depressed insulating layer having a surface formed with a depression, the method comprising the steps of:

forming a depression on a surface of an insulating layer so as to yield the depressed insulating layer;

applying a photoresist filling the depression to the surface of the insulating layer and then forming the magnetic film across the depression on the surface of the depressed insulating layer; and

performing liftoff so as to remove the photoresist buried in the depression.

22. A method of manufacturing a magnetic film sensor according to claim 20, further comprising the step of forming a magnetic layer made of a magnetic material and a conductive layer made of a conductive material on the surface of the depressed insulating layer between the step of forming the magnetic film and the step of removing the photoresist.

23. A method of manufacturing a magnetic film sensor according to claim 20, wherein the step of forming the magnetic film forms a buffer insulating layer across the depression on the surface of the depressed insulating layer after applying the photoresist filling the depression, and forms the magnetic film in contact with the buffer insulating layer.

21. A method of manufacturing a magnetic film sensor comprising a magnetic film for generating a magnetostriction and a depressed insulating layer having a surface formed with a depression, the method comprising the steps of:

forming a depression on a surface of an insulating layer so as to yield the depressed insulating layer;

applying a photoresist filling the depression to the surface of the insulating layer and then forming a coating made of an insulating material on the surface of the depressed insulating layer;

polishing the coated surface of the depressed insulating layer by CMP;

forming the magnetic film across the depression on the surface of the depressed insulating layer polished by CMP; and

performing liftoff so as to remove the photoresist buried in the depression.